FakeVim: Focus current editor before handling command line command

Action like "Switch Header/Source" need to be performed in correct
context, in this case "CppEditor.C++Editor". But while command line is
focused the context is global.

Task-number: QTCREATORBUG-9217
Change-Id: I8680e7d9612e72d23e1ef6515904941505f410d8
Reviewed-by: Eike Ziller <eike.ziller@digia.com>

src/plugins/fakevim/fakevimplugin.cpp

@@ -1719,6 +1719,11 @@ void FakeVimPluginPrivate::handleExCommand(bool *handled, const ExCommand &cmd)
     if (!handler)
         return;
 
+    // Focus editor first so actions can be executed in correct context.
+    QWidget *editor = handler->widget();
+    if (editor)
+        editor->setFocus();
+
     *handled = true;
     if (cmd.matches(_("w"), _("write")) || cmd.cmd == _("wq")) {
         // :w[rite]