* cleaned up the interface of IconMenu a bit

* compatibility with wxWdigets 2.9+: Handle MOUSE_CAPTURE_LOST event
* use wxBORDER_THEME for custom controls

* overload wxEVT_ERASE_BACKGROUND, to reduce flicker
* use wxBORDER_THEME for custom controls
* tweaked style of GalleryList a tiny bit

* overload wxEVT_ERASE_BACKGROUND, to reduce flicker

* use wxBORDER_THEME for custom controls

* compatibility with wxWdigets 2.9+: SetClippingRegion -> SetDeviceClippingRegion

compatibility with wxWdigets 2.9+: wxString::iterator::operator* aparently does not return a wxChar anymore, use cast to force conversion.

compatibility with wxWdigets 2.9+: Vector2D use *0.5 instead of /2 to prevent ambiguous conversion errors

* compatibility with wxWdigets 2.9+: Vector2D: prevent ambiguous conversion errors
* use wxBORDER_THEME for custom control

compatibility with wxWdigets 2.9+: wxString::c_str now returns an object instead of a Char*, use cast to force conversion.
TODO: This can probably be done more efficiently!

compatibility with wxWdigets 2.9+: use HandleWindowEvent instead of ProcessEvent, but this function doesn't exist in wx2.8. So, #define the former as the latter for backwards compatibility.

compatibility with wxWdigets 2.9+: Vector2D use *0.5 instead of /2 to prevent ambiguous conversion errors

compatibility with wxWdigets 2.9+: work around a bug in wx 2.9.1 (should be fixed in newer releases)