Prevents a control's clearBounds from having a width or height less than zero.
Disables selective container clearing as it can cause parts of a form not to be drawn.  We can turn this back on later with a little bit of work.
Fixes #877

Controls only need to be ordered by Z-Order when within an absolute layout.
For all other layouts created so far, controls should never overlap, and their order should be kept as it was created.
Merge pull request #885 from ablake/next

Small UI bug fixes.
Removes the need for games to call update() on forms and gamepads each frame,
and removes these calls from all tests and samples.
Also adds a few private methods to Gamepad in preparation for enabling gamepad control of UI forms.
Missed some changes to Form.cpp in previous commit.
Renamed Game::resized to Game::resizeEvent to be more consistent with other game events.
Added support for listening to game resize events from script.
Merge pull request #886 from sgrenier/next

Game resize event changes
Issue #841
Adds a very basic ImageControl class for including png images in UI forms.
Basic test of ImageControl.
Merge branch 'next' of https://github.com/blackberry/GamePlay into next
Merge pull request #887 from ablake/next

Next