A transparent layered window appears corrupted after the program stops responding, the program window is replaced by a ghost window, and then the program resumes in Windows Vista

When a program stops responding in Windows Vista, top-level windows that are owned by the program are supposed to be replaced by a ghost window until the program resumes. When the program resumes, the ghost windows are replaced by the program windows. However, in some cases, the program windows may appear corrupted when the program resumes. This problem may occur if the following conditions are true:

• The program window is transparent and uses the WS_EX_LAYERED extended window style.
• The program window was replaced with a ghost window when the program stopped responding.

For example, when this problem occurs, the program window is not correctly repainted, and instead contains information that previously appeared in the ghost window.

To resolve this problem, make sure that threads that own top-level windows consistently process windows messages.

Alternatively, you can call the DisableProcessWindowsGhosting function to disable window ghosting for the affected application. You can also use the NoGhost compatibility fix in the Application Compatibility Toolkit.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

If a top-level window stops responding to messages for more than several seconds, the system considers the window to be unresponsive. In this case, the system hides the window. The system replaces the window with a ghost window that has the same Z order, location, size, and visual attributes. This behavior lets users do the following:

• Move the window
• Resize the window
• Close the window

However, these are the only actions that are available because the application is actually not responding.