## Virtual Device Driver Reference for OS/2

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### Virtual Mouse Device Driver

This chapter describes the virtual mouse device driver (VMOUSE), which is responsible for all mouse support in multiple DOS sessions. The virtual mouse device driver also supports applications that use the BIOS INT 15h ( AH = C2h) pointing-device services.

Some of the most common mouse driver services, available through the INT 33h interface, are listed below:

Driver-state save, restore, and disable
Light-pen emulation
Miscellaneous features
Position and button-event notification
Position and button-data tracking
Selectable pel-to-coordinate and mickey-to-pel mappings
Video-mode tracking
Video pointer management (location and appearance)

There are no restrictions on any use of the INT 33h interface, even when a DOS session is in background mode. The only difference between background, focused, and foreground DOS session support is that no mouse events are posted for a background DOS session. Mouse events are posted to full-screen DOS session from the physical mouse device driver, and are posted through the Presentation Manager shield to focused, windowed DOS sessions. The pointer position should remain unchanged as long as a DOS session is in background mode, unless an application initiates pointer movement of its own. In that case, the virtual pointer position changes but nothing is drawn (not even in virtual video space).

The virtual mouse device driver also supports applications that use the BIOS INT 15h (AH=C2h) Pointing Device services.