Activate content assist only when caret enters the viewer

Content assist is now activated only when the caret moves inside the
Detail Pane, preventing interference with Expressions View and Variables
Views and enhancing the overall user experience.

Fixes : #2151

Author: SougandhS

debug/org.eclipse.debug.ui/ui/org/eclipse/debug/internal/ui/views/variables/details/DefaultDetailPane.java

@@ -1,5 +1,5 @@
 /*******************************************************************************
- *  Copyright (c) 2006, 2019 IBM Corporation and others.
+ *  Copyright (c) 2006, 2025 IBM Corporation and others.
  *
  *  This program and the accompanying materials
  *  are made available under the terms of the Eclipse Public License 2.0
@@ -82,6 +82,7 @@
 import org.eclipse.swt.custom.StyledText;
 import org.eclipse.swt.events.FocusAdapter;
 import org.eclipse.swt.events.FocusEvent;
+import org.eclipse.swt.events.FocusListener;
 import org.eclipse.swt.events.KeyEvent;
 import org.eclipse.swt.events.KeyListener;
 import org.eclipse.swt.events.MouseEvent;
@@ -591,18 +592,46 @@ public void focusLost(FocusEvent e) {
 	 * Creates the actions to add to the context menu
 	 */
 	private void createActions() {
-		TextViewerAction textAction= new TextViewerAction(fSourceViewer, ISourceViewer.CONTENTASSIST_PROPOSALS);
-		textAction.setActionDefinitionId(ITextEditorActionDefinitionIds.CONTENT_ASSIST_PROPOSALS);
-		textAction.configureAction(DetailMessages.DefaultDetailPane_Co_ntent_Assist_3, IInternalDebugCoreConstants.EMPTY_STRING,IInternalDebugCoreConstants.EMPTY_STRING);
-		textAction.setImageDescriptor(DebugPluginImages.getImageDescriptor(IDebugUIConstants.IMG_ELCL_CONTENT_ASSIST));
-		textAction.setDisabledImageDescriptor(DebugPluginImages.getImageDescriptor(IDebugUIConstants.IMG_DLCL_CONTENT_ASSIST));
-		PlatformUI.getWorkbench().getHelpSystem().setHelp(textAction, IDebugHelpContextIds.DETAIL_PANE_CONTENT_ASSIST_ACTION);
-		ActionHandler actionHandler = new ActionHandler(textAction);
-		IHandlerService handlerService = getViewSite().getService(IHandlerService.class);
-		fContentAssistActivation = handlerService.activateHandler(textAction.getActionDefinitionId(), actionHandler);
-		setAction(DETAIL_CONTENT_ASSIST_ACTION, textAction);
-
-		textAction= new TextViewerAction(fSourceViewer, ITextOperationTarget.SELECT_ALL);
+		TextViewerAction contAssistTextViewer = new TextViewerAction(fSourceViewer, ISourceViewer.CONTENTASSIST_PROPOSALS);
+
+		contAssistTextViewer.setActionDefinitionId(ITextEditorActionDefinitionIds.CONTENT_ASSIST_PROPOSALS);
+		contAssistTextViewer.configureAction(DetailMessages.DefaultDetailPane_Co_ntent_Assist_3,
+				IInternalDebugCoreConstants.EMPTY_STRING, IInternalDebugCoreConstants.EMPTY_STRING);
+		contAssistTextViewer.setImageDescriptor(DebugPluginImages.getImageDescriptor(IDebugUIConstants.IMG_ELCL_CONTENT_ASSIST));
+		contAssistTextViewer.setDisabledImageDescriptor(
+				DebugPluginImages.getImageDescriptor(IDebugUIConstants.IMG_DLCL_CONTENT_ASSIST));
+		PlatformUI.getWorkbench().getHelpSystem().setHelp(contAssistTextViewer,
+				IDebugHelpContextIds.DETAIL_PANE_CONTENT_ASSIST_ACTION);
+		ActionHandler actionHandler = new ActionHandler(contAssistTextViewer);
+		setAction(DETAIL_CONTENT_ASSIST_ACTION, contAssistTextViewer);
+
+		StyledText text = fSourceViewer.getTextWidget();
+
+		text.addCaretListener(event -> {
+			if (text.isFocusControl()) {
+				if (fContentAssistActivation == null) {
+					IHandlerService handlerService = getViewSite().getService(IHandlerService.class);
+					fContentAssistActivation = handlerService.activateHandler(contAssistTextViewer.getActionDefinitionId(),
+							actionHandler);
+				}
+			}
+		});
+
+		text.addFocusListener(new FocusListener() {
+			@Override
+			public void focusLost(FocusEvent e) {
+				if (fContentAssistActivation != null) {
+					IHandlerService handlerService = getViewSite().getService(IHandlerService.class);
+					handlerService.deactivateHandler(fContentAssistActivation);
+					fContentAssistActivation = null;
+				}
+			}
+			@Override
+			public void focusGained(FocusEvent e) {
+			}
+		});
+
+		TextViewerAction textAction = new TextViewerAction(fSourceViewer, ITextOperationTarget.SELECT_ALL);
 		textAction.configureAction(DetailMessages.DefaultDetailPane_Select__All_5, IInternalDebugCoreConstants.EMPTY_STRING,IInternalDebugCoreConstants.EMPTY_STRING);
 		textAction.setActionDefinitionId(IWorkbenchCommandConstants.EDIT_SELECT_ALL);
 		PlatformUI.getWorkbench().getHelpSystem().setHelp(textAction, IDebugHelpContextIds.DETAIL_PANE_SELECT_ALL_ACTION);