SearchHistoryMenu: improve scrolling through selection with arrow keys

Scrolling through the selection of the Search History now correctly
starts at the first item and cycles through the boundaries (ie.
scrolling down from the last item returns correctly to the first item of
the list)

fixes eclipse-platform#2139

Author: Maximilian Wittmer

bundles/org.eclipse.ui.workbench.texteditor/src/org/eclipse/ui/internal/findandreplace/overlay/SearchHistoryMenu.java

@@ -54,6 +54,7 @@ public void shellDeactivated(ShellEvent e) {
 	private int width;
 	private Table table;
 	private TableColumn column;
+	private int selectedIndexInTable = -1;
 
 	public SearchHistoryMenu(Shell parent, HistoryStore history, Consumer<String> historyEntrySelectedCallback) {
 		super(parent);
@@ -92,28 +93,58 @@ public Control createContents(Composite parent) {
 		return table;
 	}
 
+	private void moveSelectionInTable(int indexShift) {
+		selectedIndexInTable += indexShift;
+		if (selectedIndexInTable < 0) {
+			selectedIndexInTable = table.getItemCount() - 1;
+		} else if (selectedIndexInTable > table.getItemCount() - 1) {
+			selectedIndexInTable = 0;
+		}
+		table.setSelection(selectedIndexInTable);
+		historyEntrySelectedCallback.accept(table.getSelection()[0].getText());
+	}
+
 	private void attachTableListeners() {
-		table.addSelectionListener(SelectionListener.widgetSelectedAdapter(e -> {
-			TableItem[] selection = table.getSelection();
-			if (selection.length == 0) {
-				historyEntrySelectedCallback.accept(null);
-				return;
+		table.addListener(SWT.MouseMove, event -> {
+			Point point = new Point(event.x, event.y);
+			TableItem item = table.getItem(point);
+			if (item != null) {
+				table.setSelection(item);
+				selectedIndexInTable = table.getSelectionIndex();
 			}
-			String text = selection[0].getText();
-			if (text != null) {
-				historyEntrySelectedCallback.accept(text);
+		});
+		table.addKeyListener(KeyListener.keyPressedAdapter(e -> {
+			if (e.keyCode == SWT.ARROW_DOWN) {
+				moveSelectionInTable(1);
+				e.doit = false;
+			} else if (e.keyCode == SWT.ARROW_UP) {
+				moveSelectionInTable(-1);
+				e.doit = false;
+			} else if (e.keyCode == SWT.CR || e.keyCode == SWT.KEYPAD_CR) {
+				notifyParentOfSelectionInput();
+				close();
 			}
-			historyEntrySelectedCallback.accept(null);
+		}));
+		table.addSelectionListener(SelectionListener.widgetSelectedAdapter(e -> {
+			notifyParentOfSelectionInput();
 		}));
 		table.addMouseListener(MouseListener.mouseDownAdapter(e -> {
 			table.notifyListeners(SWT.Selection, null);
 			close();
 		}));
-		table.addKeyListener(KeyListener.keyPressedAdapter(e -> {
-			if (e.keyCode == SWT.CR || e.keyCode == SWT.KEYPAD_CR) {
-				close();
-			}
-		}));
+	}
+
+	private void notifyParentOfSelectionInput() {
+		TableItem[] selection = table.getSelection();
+		if (selection.length == 0) {
+			historyEntrySelectedCallback.accept(null);
+			return;
+		}
+		String text = selection[0].getText();
+		if (text != null) {
+			historyEntrySelectedCallback.accept(text);
+		}
+		historyEntrySelectedCallback.accept(null);
 	}
 
 	private void positionShell() {