Bug1432 partial, keep correct focus in more cases, not all...

Works by using the newer and better logic of ToolManager for remembering which
window to focus.

It seems, at least on Windows, that when the toolbar with the focused control
is docked after the end of a docking (of itself or another bar), then focus
remains.

If the bar with the focus is undocked and another bar docks or undocks, focus
is still lost.

src/toolbars/ToolManager.cpp

@@ -1491,11 +1491,19 @@ void ToolManager::DoneDragging()
    mDidDrag = false;
    mClicked = false;
 
+   RestoreFocus();
+}
+
+bool ToolManager::RestoreFocus()
+{
    if (mLastFocus) {
       auto temp1 = AButton::TemporarilyAllowFocus();
       auto temp2 = ASlider::TemporarilyAllowFocus();
       auto temp3 = Meter::TemporarilyAllowFocus();
       auto parent = mLastFocus->GetParent();
       mLastFocus->SetFocus();
+      return true;
    }
+
+   return false;
 }

src/toolbars/ToolManager.h

@@ -71,6 +71,8 @@ class ToolManager final : public wxEvtHandler, public wxEventFilter
 
    int FilterEvent(wxEvent &event) override;
 
+   bool RestoreFocus();
+
  private:
 
    ToolBar *Float( ToolBar *t, wxPoint & pos );