Fix: Improve UI event processing in AbstractTargetEditorTest

Stabilizes flaky UI tests by ensuring all pending UI events are processed
during editor activation. The event loop in  now
drains the event queue completely in each iteration and includes a short
sleep to allow asynchronous operations to complete.

Author: vogella

ui/org.eclipse.pde.genericeditor.extension.tests/src/org/eclipse/pde/genericeditor/extension/tests/AbstractTargetEditorTest.java

@@ -40,6 +40,7 @@
 import org.eclipse.jface.text.ITextViewer;
 import org.eclipse.jface.text.contentassist.ICompletionProposal;
 import org.eclipse.pde.internal.genericeditor.target.extension.autocomplete.TargetDefinitionContentAssist;
+import org.eclipse.swt.widgets.Display;
 import org.eclipse.ui.IEditorPart;
 import org.eclipse.ui.PlatformUI;
 import org.eclipse.ui.ide.IDE;
@@ -76,6 +77,19 @@ protected ITextViewer getTextViewerForTarget(String name) throws Exception {
 			targetFile.create(normalizedStream, true, new NullProgressMonitor());
 			IEditorPart editor = IDE.openEditor(PlatformUI.getWorkbench().getActiveWorkbenchWindow().getActivePage(),
 					targetFile, "org.eclipse.ui.genericeditor.GenericEditor");
+			PlatformUI.getWorkbench().getActiveWorkbenchWindow().getActivePage().activate(editor);
+			// Process UI events to ensure editor activation is complete
+			Display display = PlatformUI.getWorkbench().getDisplay();
+			for (int i = 0; i < 20; i++) {
+				while (display.readAndDispatch()) {
+					// Drain the event queue
+				}
+				try {
+					Thread.sleep(10);
+				} catch (InterruptedException e) {
+					// Ignore
+				}
+			}
 			return (ITextViewer) editor.getAdapter(ITextOperationTarget.class);
 		}
 	}