Control key + M on the keyboard triggers double-click functionality on Tree Items in SWT

Question

I have a double-click functionality for the tree viewers wherein the tree items expand\collapse when I double-click on them. That is completely fine but the issue is that when I press CTRL+M on the keyboard even then the tree items expand\collapse, I don't want this to happen. My code for double-clicking tree items is as follows:

private class DoubleClickListener implements IDoubleClickListener
{
  @Override
  public void doubleClick(final DoubleClickEvent event)
  {
    final IStructuredSelection selection = (IStructuredSelection)event.getSelection();
    if (selection == null || selection.isEmpty())
      return;

    final Object sel = selection.getFirstElement();

    final ITreeContentProvider provider = (ITreeContentProvider)treeViewer.getContentProvider();

    if (!provider.hasChildren(sel))
      return;

    if (treeViewer.getExpandedState(sel))
      treeViewer.collapseToLevel(sel, AbstractTreeViewer.ALL_LEVELS);
    else
      treeViewer.expandToLevel(sel, 1);
  }
}

This behavior (CTRL+m expanding tree items) only happens When I use the IDoubleClickListener interface and override the method doubleClick(), but the same behavior (CTRL+m expanding tree items) does not happen when I use : addMouseListener(new MouseListener()) and override the method : mouseDoubleClick(). Is the behavior (CTRL+m) expanding tree items related to IDoubleClickListener interface(If so what is the reason) or is this problem generic? I feel it should not be related to IDoubleClickListener, Can someone please tell me why is there a difference in using these two logic?

Answer 1

Ctrl+M is often treated the same as the Return key. The native tree control used by SWT usually treats Return as meaning expand / collapse the current tree node.

To stop this add a KeyListener to the tree and suppress the unwanted key events:

treeViewer.getTree().addKeyListener(new KeyAdapter()
  {
    @Override
    public void keyPressed(final KeyEvent event)
    {
      if (event.keyCode == SWT.CR ||
          (event.keyCode == 'm' && event.stateMask == SWT.CTRL))
       {
         event.doit = false;
       }
    }
  });

Update:

Use:

if (e.keyCode == 'm' && e.stateMask == (SWT.CTRL | SWT.SHIFT))

to test for Ctrl+Shift+m

if (e.keyCode == 'm' && e.stateMask == SWT.CTRL)

to test for Ctrl+m

if (e.keyCode == SWT.CR)

to test for Enter.