Not getting correct extents after resolution change

This is a post about an issue which I eventually have tracked down to what appears to be a bug. I have not come up with a solution for it though.

Here is the situation.

Basically I am trying to get the extents of the root control of a gui. Its sizing is set to width and height. It is a GuiChunkedBitmapCtrl.

To repro this add this to the end of the startMissionGui::onWake() function in startMissionGui.gui of a stock build:

%extent = startMissionGui.getExtent();
   echo("extent = " @ %extent);

Now launch the game and go to the start mission screen.
Check the console echo, it is the current correct resolution.
Go back to the main screen, choose options, then choose a new resolution
Go to the start mission screen and check the console echo, it is the old resolution
Go back to the main screen
Go to the start mission screen and check the console echo, it is now showing the new resolution

I originally believed this has something to do with me checking its extents before it gets resized and was correct.

The code that is actually changing the extents of the start mission screen is:
guiCanvas.cc about line 1019

//all bottom level controls should be the same dimensions as the canvas
   //this is necessary for passing mouse events accurately
   iterator i;
   for (i = begin(); i != end(); i++)
   {
      AssertFatal(static_cast<GuiControl*>((*i))->isAwake(), "GuiCanvas::renderFrame: ctrl is not awake");
      GuiControl *ctrl = static_cast<GuiControl*>(*i);
      Point2I ext = ctrl->getExtent();
      Point2I pos = ctrl->getPosition();
      
      if(pos != screenRect.point || ext != screenRect.extent)
      {
         ctrl->resize(screenRect.point, screenRect.extent);
         resetUpdateRegions();
      }
   }

Now the reason this causes a problem is because onWake actually happens BEFORE this code happens.
In the main game loop, DemoGame::main about line 506

Platform::process(); // keys, etc.
      TelConsole->process();
      TelDebugger->process();
      TimeManager::process(); // guaranteed to produce an event

onWake happens in Platform::process() while the extents resizing voodoo happens in TimeManager::process(). Thus if you are attempting to check the extents in onWake you will not get the correct result.

A possible solution is that whenever the canvas resizes we should check the root control of the canvas to make sure it is the correct size. So possibly doing the resize after the canvas gets resized might solve the problem. I would try this but I have yet to track down exactly where the canvas size gets reset.

A workaround is to force a refresh before you check the extents by using Canvas.repaint(). The problem with this method though is that you get a visible flicker of the background repainting.