CodeCompleteWindow is hidden when clicking out: thi is implemented in
EditorWindow::MouseButtonDown: if CodeCompleteWindow is visible and
the actual TextSelection of the window and the parent's TextView is
different, hide the window (I assume the user changed selection, eg.
clicked on other line, etc.).

Change-Id: Icb6bcffa837b2f7e1ccef288b9d762e27649410b