When using seamless published applications in a XenApp environment, users may experience different behaviors when moving windows around the screen. In some instances, a user will see the window contents or the background color of the server VDA while dragging the window. At other times, users will not see the contents of the window, and it will be appear to snap into place once they release the mouse button
This behavior causes the mistaken perception that XenApp is incorrectly handling the policy for “View window contents while dragging”. We find the actual cause in the nature of the seamless functionality, and in the two ways for displaying the dragging of seamless windows.
 

Background

Windows, along with other graphical user interfaces, divides an application window into two basic sections.

• The window border\title bar
• The client area (controlled by the application itself).

Desktop Window Manager (the Windows GUI compositor since Windows Vista) controls the window border and title bar, and the application controls its own client area.

Client Window Dragging

When a user drags the seamless window by the title bar, which is the most common way of moving a window, Receiver handles the window movement locally. It will communicate its last position before clicking and starting to the drag the window, and then upon release of the mouse button, will signal the VDA that the reposition is complete. At this point, the window is redrawn\repainted on the server side, and the VDA sends new images back to the client. This process minimizes resource and bandwidth usage when moving windows.
 
 

Server Side Window Dragging

Clicking and dragging the window by its client area circumvents this behavior. The VDA and receiver communicate back and forth for the duration of the entire journey of the window. The user sees the window’s contents and may see the VDA desktop background color as we follow the window position with the section of desktop being clipped and displayed on the endpoint.
NOTE: The VDA software will programmatically set “Show Window Contents while Dragging” to TRUE regardless of how this is set in Group Policy or via the Windows System Control Panel applet. We continuously show the contents of windows in order to send bitmaps via ICA to the client. This is expected behavior.
 

Special Note

 
In most applications, it is easy to determine where the title bar ends and the client area begins. Additionally, many applications do not allow the user to move the window by clicking and dragging in the client area. Applications such as Microsoft Office combine the menu bar (which is located in the client area) and title bar, and may allow users to drag the window by the client area, causing the server side redraw of the application’s path across the screen.