System File Chooser: support "approve" callback and system message dialog on Windows and Linux (not yet used in SystemFileChooser

flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatNativeLinuxLibrary.java

@@ -24,6 +24,7 @@ import java.awt.event.MouseEvent;
 import java.awt.geom.AffineTransform;
 import javax.swing.JDialog;
 import javax.swing.JFrame;
+import javax.swing.JOptionPane;
 import com.formdev.flatlaf.util.SystemInfo;
 
 /**
@@ -131,7 +132,7 @@ public class FlatNativeLinuxLibrary
 		FC_create_folders					= 1 << 5;  // default for Save
 
 	/**
-	 * Shows the Linux system file dialog
+	 * Shows the Linux/GTK system file dialog
 	 * <a href="https://docs.gtk.org/gtk3/class.FileChooserDialog.html">GtkFileChooserDialog</a>.
 	 * <p>
 	 * Uses {@code GTK_FILE_CHOOSER_ACTION_SELECT_FOLDER} if {@link #FC_select_folder} is set in parameter {@code optionsSet}.
@@ -151,6 +152,7 @@ public class FlatNativeLinuxLibrary
 	 * @param currentFolder current directory shown in the dialog; or {@code null}
 	 * @param optionsSet options to set; see {@code FOS_*} constants
 	 * @param optionsClear options to clear; see {@code FOS_*} constants
+	 * @param callback approve callback; or {@code null}
 	 * @param fileTypeIndex the file type that appears as selected (zero-based)
 	 * @param fileTypes file types that the dialog can open or save.
 	 *        Two or more strings and {@code null} are required for each filter.
@@ -164,5 +166,34 @@ public class FlatNativeLinuxLibrary
 	 */
 	public native static String[] showFileChooser( Window owner, boolean open,
 		String title, String okButtonLabel, String currentName, String currentFolder,
-		int optionsSet, int optionsClear, int fileTypeIndex, String... fileTypes );
+		int optionsSet, int optionsClear, FileChooserCallback callback,
+		int fileTypeIndex, String... fileTypes );
+
+	/** @since 3.6 */
+	public interface FileChooserCallback {
+		boolean approve( String[] files, long hwndFileDialog );
+	}
+
+	/**
+	 * Shows a GTK message box
+	 * <a href="https://docs.gtk.org/gtk3/class.MessageDialog.html">GtkMessageDialog</a>.
+	 * <p>
+	 * For use in {@link FileChooserCallback} only.
+	 *
+	 * @param hwndParent the parent of the message box
+	 * @param messageType type of message being displayed:
+	 *        {@link JOptionPane#ERROR_MESSAGE}, {@link JOptionPane#INFORMATION_MESSAGE},
+	 *        {@link JOptionPane#WARNING_MESSAGE}, {@link JOptionPane#QUESTION_MESSAGE} or
+	 *        {@link JOptionPane#PLAIN_MESSAGE}
+	 * @param primaryText primary text; if the dialog has a secondary text,
+	 *        this will appear as title in a larger bold font
+	 * @param secondaryText secondary text; shown below of primary text; or {@code null}
+	 * @param defaultButton index of the default button, which can be pressed using ENTER key
+	 * @param buttons texts of the buttons; if no buttons given the a default "OK" button is shown
+	 * @return index of pressed button; or -1 for ESC key
+	 *
+	 * @since 3.6
+	 */
+	public native static int showMessageDialog( long hwndParent, int messageType,
+		String primaryText, String secondaryText, int defaultButton, String... buttons );
 }

flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatNativeWindowsLibrary.java

@@ -218,6 +218,7 @@ public class FlatNativeWindowsLibrary
 	 * @param defaultExtension default extension to be added to file name in save dialog; or {@code null}
 	 * @param optionsSet options to set; see {@code FOS_*} constants
 	 * @param optionsClear options to clear; see {@code FOS_*} constants
+	 * @param callback approve callback; or {@code null}
 	 * @param fileTypeIndex the file type that appears as selected (zero-based)
 	 * @param fileTypes file types that the dialog can open or save.
 	 *        Pairs of strings are required for each filter.
@@ -231,5 +232,29 @@ public class FlatNativeWindowsLibrary
 	public native static String[] showFileChooser( Window owner, boolean open,
 		String title, String okButtonLabel, String fileNameLabel, String fileName,
 		String folder, String saveAsItem, String defaultFolder, String defaultExtension,
-		int optionsSet, int optionsClear, int fileTypeIndex, String... fileTypes );
+		int optionsSet, int optionsClear, FileChooserCallback callback,
+		int fileTypeIndex, String... fileTypes );
+
+	/** @since 3.6 */
+	public interface FileChooserCallback {
+		boolean approve( String[] files, long hwndFileDialog );
+	}
+
+	/**
+	 * Shows a Windows message box
+	 * <a href="https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-messagebox">MessageBox</a>.
+	 * <p>
+	 * For use in {@link FileChooserCallback} only.
+	 *
+	 * @param hwndParent the parent of the message box
+	 * @param text message to be displayed
+	 * @param caption dialog box title
+	 * @param type see <a href="https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-messagebox#parameters">MessageBox parameter uType</a>
+	 * @return see <a href="https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-messagebox#return-value">MessageBox Return value</a>
+	 * @return index of pressed button; or -1 for ESC key
+	 *
+	 * @since 3.6
+	 */
+	public native static int showMessageDialog( long hwndParent,
+		String text, String caption, int type );
 }

flatlaf-core/src/main/java/com/formdev/flatlaf/util/SystemFileChooser.java

@@ -450,7 +450,7 @@ public class SystemFileChooser
 			new Thread( () -> {
 				filenamesRef.set( showSystemDialog( owner, fc ) );
 				secondaryLoop.exit();
-			} ).start();
+			}, "FlatLaf SystemFileChooser" ).start();
 			secondaryLoop.enter();
 
 			String[] filenames = filenamesRef.get();
@@ -552,7 +552,7 @@ public class SystemFileChooser
 			// show system file dialog
 			return FlatNativeWindowsLibrary.showFileChooser( owner, open,
 				fc.getDialogTitle(), approveButtonText, null, fileName,
-				folder, saveAsItem, null, null, optionsSet, optionsClear,
+				folder, saveAsItem, null, null, optionsSet, optionsClear, null,
 				fileTypeIndex, fileTypes.toArray( new String[fileTypes.size()] ) );
 		}
 	}
@@ -693,7 +693,7 @@ public class SystemFileChooser
 			// show system file dialog
 			return FlatNativeLinuxLibrary.showFileChooser( owner, open,
 				fc.getDialogTitle(), approveButtonText, currentName, currentFolder,
-				optionsSet, optionsClear, fileTypeIndex, fileTypes.toArray( new String[fileTypes.size()] ) );
+				optionsSet, optionsClear, null, fileTypeIndex, fileTypes.toArray( new String[fileTypes.size()] ) );
 		}
 
 		private String caseInsensitiveGlobPattern( String ext ) {

flatlaf-natives/flatlaf-natives-linux/src/main/cpp/GtkFileChooser.cpp

@@ -29,6 +29,9 @@
 // declare external methods
 extern Window getWindowHandle( JNIEnv* env, JAWT* awt, jobject window, Display** display_return );
 
+// declare internal methods
+static jobjectArray fileListToStringArray( JNIEnv* env, GSList* fileList );
+
 //---- class AutoReleaseStringUTF8 --------------------------------------------
 
 class AutoReleaseStringUTF8 {
@@ -142,10 +145,37 @@ static void handle_realize( GtkWidget* dialog, gpointer data ) {
 	g_object_unref( gdkOwner );
 }
 
+struct ResponseData {
+	JNIEnv* env;
+	jobject callback;
+	GSList* fileList;
+
+	ResponseData( JNIEnv* _env, jobject _callback ) {
+		env = _env;
+		callback = _callback;
+		fileList = NULL;
+	}
+};
+
 static void handle_response( GtkWidget* dialog, gint responseId, gpointer data ) {
 	// get filenames if user pressed OK
-	if( responseId == GTK_RESPONSE_ACCEPT )
+	if( responseId == GTK_RESPONSE_ACCEPT ) {
-		*((GSList**)data) = gtk_file_chooser_get_filenames( GTK_FILE_CHOOSER( dialog ) );
+		ResponseData *response = static_cast<ResponseData*>( data );
+		if( response->callback != NULL ) {
+			GSList* fileList = gtk_file_chooser_get_filenames( GTK_FILE_CHOOSER( dialog ) );
+			jobjectArray files = fileListToStringArray( response->env, fileList );
+
+			GtkWindow* window = GTK_WINDOW( dialog );
+
+			// invoke callback: boolean approve( String[] files, long hwnd );
+			jclass cls = response->env->GetObjectClass( response->callback );
+			jmethodID approveID = response->env->GetMethodID( cls, "approve", "([Ljava/lang/String;J)Z" );
+			if( approveID != NULL && !response->env->CallBooleanMethod( response->callback, approveID, files, window ) )
+				return; // keep dialog open
+		}
+
+		response->fileList = gtk_file_chooser_get_filenames( GTK_FILE_CHOOSER( dialog ) );
+	}
 
 	// hide/destroy file dialog and quit loop
 	gtk_widget_hide( dialog );
@@ -159,7 +189,7 @@ extern "C"
 JNIEXPORT jobjectArray JNICALL Java_com_formdev_flatlaf_ui_FlatNativeLinuxLibrary_showFileChooser
 	( JNIEnv* env, jclass cls, jobject owner, jboolean open,
 		jstring title, jstring okButtonLabel, jstring currentName, jstring currentFolder,
-		jint optionsSet, jint optionsClear, jint fileTypeIndex, jobjectArray fileTypes )
+		jint optionsSet, jint optionsClear, jobject callback, jint fileTypeIndex, jobjectArray fileTypes )
 {
 	// initialize GTK
 	if( !gtk_init_check( NULL, NULL ) )
@@ -222,8 +252,8 @@ JNIEXPORT jobjectArray JNICALL Java_com_formdev_flatlaf_ui_FlatNativeLinuxLibrar
 
 	// show dialog
 	// (similar to what's done in sun_awt_X11_GtkFileDialogPeer.c)
-	GSList* fileList = NULL;
+	ResponseData responseData( env, callback );
-	g_signal_connect( dialog, "response", G_CALLBACK( handle_response ), &fileList );
+	g_signal_connect( dialog, "response", G_CALLBACK( handle_response ), &responseData );
 	gtk_widget_show( dialog );
 
 	// necessary to bring file dialog to the front (and make it active)
@@ -241,10 +271,14 @@ JNIEXPORT jobjectArray JNICALL Java_com_formdev_flatlaf_ui_FlatNativeLinuxLibrar
 	gtk_main();
 
 	// canceled?
-	if( fileList == NULL )
+	if( responseData.fileList == NULL )
 		return newJavaStringArray( env, 0 );
 
 	// convert GSList to Java string array
+	return fileListToStringArray( env, responseData.fileList );
+}
+
+static jobjectArray fileListToStringArray( JNIEnv* env, GSList* fileList ) {
 	guint count = g_slist_length( fileList );
 	jobjectArray array = newJavaStringArray( env, count );
 	GSList* it = fileList;
@@ -259,3 +293,52 @@ JNIEXPORT jobjectArray JNICALL Java_com_formdev_flatlaf_ui_FlatNativeLinuxLibrar
 	g_slist_free( fileList );
 	return array;
 }
+
+
+extern "C"
+JNIEXPORT jint JNICALL Java_com_formdev_flatlaf_ui_FlatNativeLinuxLibrary_showMessageDialog
+	( JNIEnv* env, jclass cls, jlong hwndParent, jint messageType, jstring primaryText, jstring secondaryText,
+		jint defaultButton, jobjectArray buttons )
+{
+	GtkWindow* window = (GtkWindow*) hwndParent;
+
+	// convert message type
+	GtkMessageType gmessageType;
+	switch( messageType ) {
+		case /* JOptionPane.ERROR_MESSAGE */       0: gmessageType = GTK_MESSAGE_ERROR; break;
+		case /* JOptionPane.INFORMATION_MESSAGE */ 1: gmessageType = GTK_MESSAGE_INFO; break;
+		case /* JOptionPane.WARNING_MESSAGE */     2: gmessageType = GTK_MESSAGE_WARNING; break;
+		case /* JOptionPane.QUESTION_MESSAGE */    3: gmessageType = GTK_MESSAGE_QUESTION; break;
+		default:
+		case /* JOptionPane.PLAIN_MESSAGE */      -1: gmessageType = GTK_MESSAGE_OTHER; break;
+	}
+
+	// convert Java strings to C strings
+	AutoReleaseStringUTF8 cprimaryText( env, primaryText );
+	AutoReleaseStringUTF8 csecondaryText( env, secondaryText );
+
+	// create GTK file chooser dialog
+	// https://docs.gtk.org/gtk3/class.MessageDialog.html
+	jint buttonCount = env->GetArrayLength( buttons );
+	GtkWidget* dialog = gtk_message_dialog_new( window, GTK_DIALOG_MODAL, gmessageType,
+		(buttonCount > 0) ? GTK_BUTTONS_NONE : GTK_BUTTONS_OK,
+		"%s", (const gchar*) cprimaryText );
+	if( csecondaryText != NULL )
+		gtk_message_dialog_format_secondary_text( GTK_MESSAGE_DIALOG( dialog ), "%s", (const gchar*) csecondaryText );
+
+	// add buttons
+	for( int i = 0; i < buttonCount; i++ ) {
+		AutoReleaseStringUTF8 str( env, (jstring) env->GetObjectArrayElement( buttons, i ) );
+		gtk_dialog_add_button( GTK_DIALOG( dialog ), str, i );
+	}
+
+	// set default button
+	gtk_dialog_set_default_response( GTK_DIALOG( dialog ), MIN( MAX( defaultButton, 0 ), buttonCount - 1 ) );
+
+	// show message dialog
+	gint responseID = gtk_dialog_run( GTK_DIALOG( dialog ) );
+	gtk_widget_destroy( dialog );
+
+	// return -1 if closed with ESC key
+	return (responseID >= 0) ? responseID : -1;
+}

flatlaf-natives/flatlaf-natives-linux/src/main/headers/com_formdev_flatlaf_ui_FlatNativeLinuxLibrary.h

@@ -40,10 +40,18 @@ JNIEXPORT jboolean JNICALL Java_com_formdev_flatlaf_ui_FlatNativeLinuxLibrary_xS
 /*
  * Class:     com_formdev_flatlaf_ui_FlatNativeLinuxLibrary
  * Method:    showFileChooser
- * Signature: (Ljava/awt/Window;ZLjava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;III[Ljava/lang/String;)[Ljava/lang/String;
+ * Signature: (Ljava/awt/Window;ZLjava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;IILcom/formdev/flatlaf/ui/FlatNativeLinuxLibrary/FileChooserCallback;I[Ljava/lang/String;)[Ljava/lang/String;
  */
 JNIEXPORT jobjectArray JNICALL Java_com_formdev_flatlaf_ui_FlatNativeLinuxLibrary_showFileChooser
-  (JNIEnv *, jclass, jobject, jboolean, jstring, jstring, jstring, jstring, jint, jint, jint, jobjectArray);
+  (JNIEnv *, jclass, jobject, jboolean, jstring, jstring, jstring, jstring, jint, jint, jobject, jint, jobjectArray);
+
+/*
+ * Class:     com_formdev_flatlaf_ui_FlatNativeLinuxLibrary
+ * Method:    showMessageDialog
+ * Signature: (JILjava/lang/String;Ljava/lang/String;I[Ljava/lang/String;)I
+ */
+JNIEXPORT jint JNICALL Java_com_formdev_flatlaf_ui_FlatNativeLinuxLibrary_showMessageDialog
+  (JNIEnv *, jclass, jlong, jint, jstring, jstring, jint, jobjectArray);
 
 #ifdef __cplusplus
 }

flatlaf-natives/flatlaf-natives-windows/build.gradle.kts

@@ -64,7 +64,7 @@ tasks {
 		compilerArgs.addAll( toolChain.map {
 			when( it ) {
 				is Gcc, is Clang -> listOf( "-O2", "-DUNICODE" )
-				is VisualCpp -> listOf( "/O2", "/Zl", "/GS-", "/DUNICODE" )
+				is VisualCpp -> listOf( "/O2", "/GS-", "/DUNICODE" )
 				else -> emptyList()
 			}
 		} )
@@ -81,7 +81,7 @@ tasks {
 		linkerArgs.addAll( toolChain.map {
 			when( it ) {
 				is Gcc, is Clang -> listOf( "-lUser32", "-lGdi32", "-lshell32", "-lAdvAPI32", "-lKernel32", "-lDwmapi", "-lOle32", "-luuid" )
-				is VisualCpp -> listOf( "User32.lib", "Gdi32.lib", "shell32.lib", "AdvAPI32.lib", "Kernel32.lib", "Dwmapi.lib", "Ole32.lib", "uuid.lib", "/NODEFAULTLIB" )
+				is VisualCpp -> listOf( "User32.lib", "Gdi32.lib", "shell32.lib", "AdvAPI32.lib", "Kernel32.lib", "Dwmapi.lib", "Ole32.lib", "uuid.lib" )
 				else -> emptyList()
 			}
 		} )

flatlaf-natives/flatlaf-natives-windows/src/main/cpp/WinFileChooser.cpp

@@ -29,6 +29,9 @@
 // declare external methods
 extern HWND getWindowHandle( JNIEnv* env, jobject window );
 
+// declare internal methods
+static jobjectArray getFiles( JNIEnv* env, jboolean open, IFileDialog* dialog );
+
 //---- class AutoReleasePtr ---------------------------------------------------
 
 template<class T> class AutoReleasePtr {
@@ -38,6 +41,10 @@ public:
 	AutoReleasePtr() {
 		ptr = NULL;
 	}
+	AutoReleasePtr( T* p ) {
+		ptr = p;
+		ptr->AddRef();
+	}
 	~AutoReleasePtr() {
 		if( ptr != NULL )
 			ptr->Release();
@@ -126,6 +133,86 @@ public:
 	}
 };
 
+//---- class DialogEventHandler -----------------------------------------------
+
+// see https://github.com/microsoft/Windows-classic-samples/blob/main/Samples/Win7Samples/winui/shell/appplatform/commonfiledialog/CommonFileDialogApp.cpp
+
+class DialogEventHandler : public IFileDialogEvents {
+	JNIEnv* env;
+	jboolean open;
+	jobject callback;
+	LONG refCount = 1;
+
+public:
+	DialogEventHandler( JNIEnv* _env, jboolean _open, jobject _callback ) {
+		env = _env;
+		open = _open;
+		callback = _callback;
+	}
+
+	//---- IFileDialogEvents methods ----
+
+	IFACEMETHODIMP OnFileOk( IFileDialog* dialog ) {
+		if( callback == NULL )
+			return S_OK;
+
+		// get files
+		jobjectArray files;
+		if( open ) {
+			AutoReleasePtr<IFileOpenDialog> openDialog;
+			HRESULT hr = dialog->QueryInterface( &openDialog );
+			files = SUCCEEDED( hr ) ? getFiles( env, true, openDialog ) : getFiles( env, false, dialog );
+		} else
+			files = getFiles( env, false, dialog );
+
+		// get hwnd of file dialog
+		HWND hwndFileDialog = 0;
+		AutoReleasePtr<IOleWindow> window;
+		if( SUCCEEDED( dialog->QueryInterface( &window ) ) )
+			window->GetWindow( &hwndFileDialog );
+
+		// invoke callback: boolean approve( String[] files, long hwnd );
+		jclass cls = env->GetObjectClass( callback );
+		jmethodID approveID = env->GetMethodID( cls, "approve", "([Ljava/lang/String;J)Z" );
+		if( approveID == NULL )
+			return S_OK;
+		return env->CallBooleanMethod( callback, approveID, files, hwndFileDialog ) ? S_OK : S_FALSE;
+	}
+
+	IFACEMETHODIMP OnFolderChange( IFileDialog* ) { return S_OK; }
+	IFACEMETHODIMP OnFolderChanging( IFileDialog*, IShellItem* ) { return S_OK; }
+	IFACEMETHODIMP OnHelp( IFileDialog* ) { return S_OK; }
+	IFACEMETHODIMP OnSelectionChange( IFileDialog* ) { return S_OK; }
+	IFACEMETHODIMP OnShareViolation( IFileDialog*, IShellItem*, FDE_SHAREVIOLATION_RESPONSE* ) { return S_OK; }
+	IFACEMETHODIMP OnTypeChange( IFileDialog*pfd ) { return S_OK; }
+	IFACEMETHODIMP OnOverwrite( IFileDialog*, IShellItem*, FDE_OVERWRITE_RESPONSE* ) { return S_OK; }
+
+	//---- IUnknown methods ----
+
+	IFACEMETHODIMP QueryInterface( REFIID riid, void** ppv ) {
+		if( riid != IID_IFileDialogEvents && riid != IID_IUnknown )
+			return E_NOINTERFACE;
+
+		*ppv = static_cast<IFileDialogEvents*>( this );
+		AddRef();
+		return S_OK;
+	}
+
+	IFACEMETHODIMP_(ULONG) AddRef() {
+		return InterlockedIncrement( &refCount );
+	}
+
+	IFACEMETHODIMP_(ULONG) Release() {
+		LONG newRefCount = InterlockedDecrement( &refCount );
+		if( newRefCount == 0 )
+			delete this;
+		return newRefCount;
+	}
+
+private:
+	~DialogEventHandler() {}
+};
+
 //---- class CoInitializer ----------------------------------------------------
 
 class CoInitializer {
@@ -163,7 +250,7 @@ JNIEXPORT jobjectArray JNICALL Java_com_formdev_flatlaf_ui_FlatNativeWindowsLibr
 	( JNIEnv* env, jclass cls, jobject owner, jboolean open,
 		jstring title, jstring okButtonLabel, jstring fileNameLabel, jstring fileName,
 		jstring folder, jstring saveAsItem, jstring defaultFolder, jstring defaultExtension,
-		jint optionsSet, jint optionsClear, jint fileTypeIndex, jobjectArray fileTypes )
+		jint optionsSet, jint optionsClear, jobject callback, jint fileTypeIndex, jobjectArray fileTypes )
 {
 	// initialize COM library
 	CoInitializer coInitializer;
@@ -226,20 +313,31 @@ JNIEXPORT jobjectArray JNICALL Java_com_formdev_flatlaf_ui_FlatNativeWindowsLibr
 			CHECK_HRESULT( dialog->SetFileTypeIndex( min( fileTypeIndex + 1, specs.count ) ) );
 	}
 
+	// add event handler
+	AutoReleasePtr<DialogEventHandler> handler( new DialogEventHandler( env, open, callback ) );
+	DWORD dwCookie = 0;
+	CHECK_HRESULT( dialog->Advise( handler, &dwCookie ) );
+
 	// show dialog
 	HWND hwndOwner = (owner != NULL) ? getWindowHandle( env, owner ) : NULL;
 	HRESULT hr = dialog->Show( hwndOwner );
+	dialog->Unadvise( dwCookie );
 	if( hr == HRESULT_FROM_WIN32(ERROR_CANCELLED) )
 		return newJavaStringArray( env, 0 );
 	CHECK_HRESULT( hr );
 
-	// convert shell items to Java string array
+	// get selected files as Java string array
+	return getFiles( env, open, dialog );
+}
+
+static jobjectArray getFiles( JNIEnv* env, jboolean open, IFileDialog* dialog ) {
 	if( open ) {
 		AutoReleasePtr<IShellItemArray> shellItems;
 		DWORD count;
 		CHECK_HRESULT( ((IFileOpenDialog*)(IFileDialog*)dialog)->GetResults( &shellItems ) );
 		CHECK_HRESULT( shellItems->GetCount( &count ) );
 
+		// convert shell items to Java string array
 		jobjectArray array = newJavaStringArray( env, count );
 		for( int i = 0; i < count; i++ ) {
 			AutoReleasePtr<IShellItem> shellItem;
@@ -260,6 +358,7 @@ JNIEXPORT jobjectArray JNICALL Java_com_formdev_flatlaf_ui_FlatNativeWindowsLibr
 		CHECK_HRESULT( dialog->GetResult( &shellItem ) );
 		CHECK_HRESULT( shellItem->GetDisplayName( SIGDN_FILESYSPATH, &path ) );
 
+		// convert shell item to Java string array
 		jstring jpath = newJavaString( env, path );
 		CoTaskMemFree( path );
 
@@ -270,3 +369,15 @@ JNIEXPORT jobjectArray JNICALL Java_com_formdev_flatlaf_ui_FlatNativeWindowsLibr
 		return array;
 	}
 }
+
+
+extern "C"
+JNIEXPORT jint JNICALL Java_com_formdev_flatlaf_ui_FlatNativeWindowsLibrary_showMessageDialog
+	( JNIEnv* env, jclass cls, jlong hwndParent, jstring text, jstring caption, jint type )
+{
+	// convert Java strings to C strings
+	AutoReleaseString ctext( env, text );
+	AutoReleaseString ccaption( env, caption );
+
+	return ::MessageBox( reinterpret_cast<HWND>( hwndParent ), ctext, ccaption, type );
+}

flatlaf-natives/flatlaf-natives-windows/src/main/headers/com_formdev_flatlaf_ui_FlatNativeWindowsLibrary.h

@@ -116,10 +116,18 @@ JNIEXPORT jboolean JNICALL Java_com_formdev_flatlaf_ui_FlatNativeWindowsLibrary_
 /*
  * Class:     com_formdev_flatlaf_ui_FlatNativeWindowsLibrary
  * Method:    showFileChooser
- * Signature: (Ljava/awt/Window;ZLjava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;III[Ljava/lang/String;)[Ljava/lang/String;
+ * Signature: (Ljava/awt/Window;ZLjava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;Ljava/lang/String;IILcom/formdev/flatlaf/ui/FlatNativeWindowsLibrary/FileChooserCallback;I[Ljava/lang/String;)[Ljava/lang/String;
  */
 JNIEXPORT jobjectArray JNICALL Java_com_formdev_flatlaf_ui_FlatNativeWindowsLibrary_showFileChooser
-  (JNIEnv *, jclass, jobject, jboolean, jstring, jstring, jstring, jstring, jstring, jstring, jstring, jstring, jint, jint, jint, jobjectArray);
+  (JNIEnv *, jclass, jobject, jboolean, jstring, jstring, jstring, jstring, jstring, jstring, jstring, jstring, jint, jint, jobject, jint, jobjectArray);
+
+/*
+ * Class:     com_formdev_flatlaf_ui_FlatNativeWindowsLibrary
+ * Method:    showMessageDialog
+ * Signature: (JLjava/lang/String;Ljava/lang/String;I)I
+ */
+JNIEXPORT jint JNICALL Java_com_formdev_flatlaf_ui_FlatNativeWindowsLibrary_showMessageDialog
+  (JNIEnv *, jclass, jlong, jstring, jstring, jint);
 
 #ifdef __cplusplus
 }

flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatSystemFileChooserLinuxTest.java

@@ -124,10 +124,20 @@ public class FlatSystemFileChooserLinuxTest
 		}
 		int fileTypeIndex = fileTypeIndexSlider.getValue();
 
+		FlatNativeLinuxLibrary.FileChooserCallback callback = (files, hwndFileDialog) -> {
+			System.out.println( "  -- callback " + hwndFileDialog + "  " + Arrays.toString( files ) );
+			if( showMessageDialogOnOKCheckBox.isSelected() ) {
+				System.out.println( FlatNativeLinuxLibrary.showMessageDialog( hwndFileDialog,
+					JOptionPane.INFORMATION_MESSAGE,
+					"primary text", "secondary text", 1, "Yes", "No" ) );
+			}
+			return true;
+		};
+
 		if( direct ) {
 			String[] files = FlatNativeLinuxLibrary.showFileChooser( owner, open,
 				title, okButtonLabel, currentName, currentFolder,
-				optionsSet.get(), optionsClear.get(), fileTypeIndex, fileTypes );
+				optionsSet.get(), optionsClear.get(), callback, fileTypeIndex, fileTypes );
 
 			filesField.setText( (files != null) ? Arrays.toString( files ).replace( ',', '\n' ) : "null" );
 		} else {
@@ -137,7 +147,7 @@ public class FlatSystemFileChooserLinuxTest
 			new Thread( () -> {
 				String[] files = FlatNativeLinuxLibrary.showFileChooser( owner, open,
 					title, okButtonLabel, currentName, currentFolder,
-					optionsSet.get(), optionsClear.get(), fileTypeIndex, fileTypes2 );
+					optionsSet.get(), optionsClear.get(), callback, fileTypeIndex, fileTypes2 );
 
 				System.out.println( "    secondaryLoop.exit() returned " + secondaryLoop.exit() );
 
@@ -248,6 +258,7 @@ public class FlatSystemFileChooserLinuxTest
 		saveButton = new JButton();
 		openDirectButton = new JButton();
 		saveDirectButton = new JButton();
+		showMessageDialogOnOKCheckBox = new JCheckBox();
 		filesScrollPane = new JScrollPane();
 		filesField = new JTextArea();
 
@@ -397,6 +408,10 @@ public class FlatSystemFileChooserLinuxTest
 		saveDirectButton.addActionListener(e -> saveDirect());
 		add(saveDirectButton, "cell 0 7 3 1");
 
+		//---- showMessageDialogOnOKCheckBox ----
+		showMessageDialogOnOKCheckBox.setText("show message dialog on OK");
+		add(showMessageDialogOnOKCheckBox, "cell 0 7 3 1");
+
 		//======== filesScrollPane ========
 		{
 
@@ -443,6 +458,7 @@ public class FlatSystemFileChooserLinuxTest
 	private JButton saveButton;
 	private JButton openDirectButton;
 	private JButton saveDirectButton;
+	private JCheckBox showMessageDialogOnOKCheckBox;
 	private JScrollPane filesScrollPane;
 	private JTextArea filesField;
 	// JFormDesigner - End of variables declaration  //GEN-END:variables

flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatSystemFileChooserLinuxTest.jfd

@@ -1,4 +1,4 @@
-JFDML JFormDesigner: "8.3" encoding: "UTF-8"
+JFDML JFormDesigner: "8.2.2.0.9999" Java: "21.0.1" encoding: "UTF-8"
 
 new FormModel {
 	contentType: "form/swing"
@@ -198,6 +198,12 @@ new FormModel {
 			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
 				"value": "cell 0 7 3 1"
 			} )
+			add( new FormComponent( "javax.swing.JCheckBox" ) {
+				name: "showMessageDialogOnOKCheckBox"
+				"text": "show message dialog on OK"
+			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+				"value": "cell 0 7 3 1"
+			} )
 			add( new FormContainer( "javax.swing.JScrollPane", new FormLayoutManager( class javax.swing.JScrollPane ) ) {
 				name: "filesScrollPane"
 				add( new FormComponent( "javax.swing.JTextArea" ) {

flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatSystemFileChooserWindowsTest.java

@@ -139,11 +139,21 @@ public class FlatSystemFileChooserWindowsTest
 			fileTypes = fileTypesStr.trim().split( "[,]+" );
 		int fileTypeIndex = fileTypeIndexSlider.getValue();
 
+		FlatNativeWindowsLibrary.FileChooserCallback callback = (files, hwndFileDialog) -> {
+			System.out.println( "  -- callback " + hwndFileDialog + "  " + Arrays.toString( files ) );
+			if( showMessageDialogOnOKCheckBox.isSelected() ) {
+				System.out.println( FlatNativeWindowsLibrary.showMessageDialog( hwndFileDialog,
+					"some text", "title",
+					/* MB_ICONINFORMATION */ 0x00000040 | /* MB_YESNO */ 0x00000004 ) );
+			}
+			return true;
+		};
+
 		if( direct ) {
 			String[] files = FlatNativeWindowsLibrary.showFileChooser( owner, open,
 				title, okButtonLabel, fileNameLabel, fileName,
 				folder, saveAsItem, defaultFolder, defaultExtension,
-				optionsSet.get(), optionsClear.get(), fileTypeIndex, fileTypes );
+				optionsSet.get(), optionsClear.get(), callback, fileTypeIndex, fileTypes );
 
 			filesField.setText( (files != null) ? Arrays.toString( files ).replace( ',', '\n' ) : "null" );
 		} else {
@@ -154,7 +164,7 @@ public class FlatSystemFileChooserWindowsTest
 				String[] files = FlatNativeWindowsLibrary.showFileChooser( owner, open,
 					title, okButtonLabel, fileNameLabel, fileName,
 					folder, saveAsItem, defaultFolder, defaultExtension,
-					optionsSet.get(), optionsClear.get(), fileTypeIndex, fileTypes2 );
+					optionsSet.get(), optionsClear.get(), callback, fileTypeIndex, fileTypes2 );
 
 				System.out.println( "    secondaryLoop.exit() returned " + secondaryLoop.exit() );
 
@@ -290,6 +300,7 @@ public class FlatSystemFileChooserWindowsTest
 		saveButton = new JButton();
 		openDirectButton = new JButton();
 		saveDirectButton = new JButton();
+		showMessageDialogOnOKCheckBox = new JCheckBox();
 		filesScrollPane = new JScrollPane();
 		filesField = new JTextArea();
 
@@ -534,6 +545,10 @@ public class FlatSystemFileChooserWindowsTest
 		saveDirectButton.addActionListener(e -> saveDirect());
 		add(saveDirectButton, "cell 0 11 3 1");
 
+		//---- showMessageDialogOnOKCheckBox ----
+		showMessageDialogOnOKCheckBox.setText("show message dialog on OK");
+		add(showMessageDialogOnOKCheckBox, "cell 0 11 3 1");
+
 		//======== filesScrollPane ========
 		{
 
@@ -605,6 +620,7 @@ public class FlatSystemFileChooserWindowsTest
 	private JButton saveButton;
 	private JButton openDirectButton;
 	private JButton saveDirectButton;
+	private JCheckBox showMessageDialogOnOKCheckBox;
 	private JScrollPane filesScrollPane;
 	private JTextArea filesField;
 	// JFormDesigner - End of variables declaration  //GEN-END:variables

flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatSystemFileChooserWindowsTest.jfd

@@ -343,6 +343,12 @@ new FormModel {
 			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
 				"value": "cell 0 11 3 1"
 			} )
+			add( new FormComponent( "javax.swing.JCheckBox" ) {
+				name: "showMessageDialogsOnOKCheckBox"
+				"text": "show message dialog on OK"
+			}, new FormLayoutConstraints( class net.miginfocom.layout.CC ) {
+				"value": "cell 0 11 3 1"
+			} )
 			add( new FormContainer( "javax.swing.JScrollPane", new FormLayoutManager( class javax.swing.JScrollPane ) ) {
 				name: "filesScrollPane"
 				add( new FormComponent( "javax.swing.JTextArea" ) {