[uxtheme]

[uxtheme]
- Properly disable themes when theme hooks are removed
- Add WND_CONTEXT a per window struct that will hold several theme specific information. For now it contains only theme region related info. It will be stored as a window property
- Implement destroying WND_CONTEXT for every window when theme hooks are removed or when the window is destroyed
- Hook the messages that are sent to dialogs, like they are hooked for normal windows
- Hook SetWindowRgn call from user32. When an application calls it, uxtheme will stop setting window region on its own region
- Implement setting a custom window region for windows after receiving WM_WINDOWPOSCHANGED message using GetThemeBackgroundRegion

svn path=/branches/GSoC_2011/ThemesSupport/; revision=53262