Theme Editor: paint current line highlight always in the line where the caret is, which makes it easier to locate current match when using find/replace

RSyntaxTextArea paints line highlight only if selection is empty (caret dot == mark)

flatlaf-theme-editor/src/main/java/com/formdev/flatlaf/themeeditor/FlatRSyntaxTextAreaUI.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2021 FormDev Software GmbH
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.formdev.flatlaf.themeeditor;
+
+import java.awt.Graphics;
+import java.awt.Rectangle;
+import javax.swing.JComponent;
+import javax.swing.text.BadLocationException;
+import org.fife.ui.rsyntaxtextarea.RSyntaxTextAreaUI;
+
+/**
+ * @author Karl Tauber
+ */
+class FlatRSyntaxTextAreaUI
+	extends RSyntaxTextAreaUI
+{
+	FlatRSyntaxTextAreaUI( JComponent rSyntaxTextArea ) {
+		super( rSyntaxTextArea );
+	}
+
+	@Override
+	protected void paintCurrentLineHighlight( Graphics g, Rectangle visibleRect ) {
+		if( !textArea.getHighlightCurrentLine() )
+			return;
+
+		// paint current line highlight always in the line where the caret is
+		try {
+			int dot = textArea.getCaret().getDot();
+			Rectangle dotRect = textArea.modelToView( dot );
+			int height = textArea.getLineHeight();
+
+			g.setColor( textArea.getCurrentLineHighlightColor() );
+			g.fillRect( visibleRect.x, dotRect.y, visibleRect.width, height );
+		} catch( BadLocationException ex ) {
+			super.paintCurrentLineHighlight( g, visibleRect );
+		}
+	}
+}

flatlaf-theme-editor/src/main/java/com/formdev/flatlaf/themeeditor/FlatSyntaxTextArea.java

@@ -31,6 +31,7 @@ import javax.swing.text.BadLocationException;
 import org.fife.ui.rsyntaxtextarea.TextEditorPane;
 import org.fife.ui.rsyntaxtextarea.Token;
 import org.fife.ui.rtextarea.RTextArea;
+import org.fife.ui.rtextarea.RTextAreaUI;
 import com.formdev.flatlaf.UIDefaultsLoaderAccessor;
 import com.formdev.flatlaf.themeeditor.FlatSyntaxTextAreaActions.DuplicateLinesAction;
 
@@ -68,6 +69,11 @@ class FlatSyntaxTextArea
 		inputMap.put( KeyStroke.getKeyStroke( KeyEvent.VK_DOWN, defaultModifier|alt), FlatSyntaxTextAreaActions.duplicateLinesDownAction );
 	}
 
+	@Override
+	protected RTextAreaUI createRTextAreaUI() {
+		return new FlatRSyntaxTextAreaUI( this );
+	}
+
 	boolean isUseColorOfColorTokens() {
 		return useColorOfColorTokens;
 	}