Popup: no longer reuse popup windows for menus to avoid immediately closing dialogs on ChromeOS (issue #1029)

added system property `flatlaf.reuseVisiblePopupWindow`

CHANGELOG.md

@@ -15,6 +15,8 @@ FlatLaf Change Log
 - Tree and List: Fixed painting of rounded drop backgrounds. (issue #1023)
 - Popup: Showing tooltip in inactive window brought that window to front (made
   it active) and potentially hid the previously active window. (issue #1037)
+- Popup: No longer reuse popup windows for menus to avoid immediately closing
+  dialogs on ChromeOS. (issue #1029)
 - macOS: Fixed window "flashing" when switching from a light to a dark theme (or
   vice versa). Especially when using animated theme changer (see
   [FlatLaf Extras](flatlaf-extras)).

flatlaf-core/src/main/java/com/formdev/flatlaf/FlatSystemProperties.java

@@ -16,6 +16,7 @@
 
 package com.formdev.flatlaf;
 
+import javax.swing.JPopupMenu;
 import javax.swing.SwingUtilities;
 import com.formdev.flatlaf.util.UIScale;
 
@@ -147,6 +148,25 @@ public interface FlatSystemProperties
 	 */
 	String USE_ROUNDED_POPUP_BORDER = "flatlaf.useRoundedPopupBorder";
 
+	/**
+	 * Species whether popup windows may be reused without (temporary) hiding them.
+	 * E.g. if "moving" a tooltip to follow the mouse pointer, normally it is necessary
+	 * to hide the tooltip and show it again at the new location, which causes some
+	 * flicker with heavy-weight popup windows that FlatLaf uses on all platforms.
+	 * <p>
+	 * If {@code true}, hiding popup window is deferred for an event cycle,
+	 * which allows reusing still visible popup window and avoids flicker when "moving" the popup.
+	 * <p>
+	 * Note that {@link JPopupMenu} popup windows (menus and combobox lists) are newer reused.
+	 * <p>
+	 * <strong>Allowed Values</strong> {@code false} and {@code true}<br>
+	 * <strong>Default</strong> {@code true}
+	 *
+	 * @since 3.7
+	 */
+	String REUSE_VISIBLE_POPUP_WINDOW = "flatlaf.reuseVisiblePopupWindow";
+
+
 	/**
 	 * Specifies whether vertical text position is corrected when UI is scaled on HiDPI screens.
 	 * <p>

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

@@ -676,8 +676,11 @@ public class FlatPopupFactory
 				return;
 			disposed = true;
 
-			// immediately hide non-heavy weight popups or combobox popups
-			if( !(popupWindow instanceof JWindow) || contents instanceof BasicComboPopup ) {
+			// immediately hide non-heavy weight popups, popup menus and combobox popups
+			// of if system property is false
+			if( !(popupWindow instanceof JWindow) || contents instanceof JPopupMenu ||
+				!FlatSystemProperties.getBoolean( FlatSystemProperties.REUSE_VISIBLE_POPUP_WINDOW, true ) )
+			{
 				hideImpl();
 				return;
 			}