PRB: Window Dragged Close to Screen Edge Becomes Invisible

The information in this article applies to:

• Microsoft Windows Software Development Kit (SDK) for Windows versions 3.1 and 3.0

SYMPTOMS

If the user uses the mouse to drag the left edge of a window (or dialog box) within a few pixels of the right edge of the display and releases the mouse button, the window moves completely off the display. The user can't use the mouse to bring the window back into the display.

CAUSE

The window is created with the CS_BYTEALIGNCLIENT or CS_BYTEALIGNWINDOW class style bit set. When the user releases the mouse button, the window moves right to byte-align itself. However, because the byte boundary is off the screen, the entire window becomes invisible.

RESOLUTION

There are two methods to work around this problem:

• Give the window a system menu. This will prevent it from disappearing off the right edge of the screen.

  -or-

• Calculate the size of any window that has a caption bar to conform to the following formula:

        horizontal_size modulo 8 <= 4