3 The Mouse
3.3 Window system input
Whenever you type a character or perform some action with the mouse, whether it is a simple movement or a mouse click, the Window Tool Kit receives the input. This input is processed in a specific order. It is important to understand this order so that you can use the input capabilities of the window system correctly. The processing order depends on the type of input that is received, as follows:
- If the character has been defined as an interrupt character, its associated function is invoked. If the character is not an interrupt character, it is queued on the mouse input stream associated with the current keyboard input stream, which is the value of the function
keyboard-input. See Chapter 6, "Keyboard Interrupt Characters" for more information. - If the input is a mouse event, the following actions take place:
- The mouse position and mouse button states are changed.
- If the mouse input stream that is the value of the function
mouse-input is currently queuing mouse events, the event is put on its queue. - Any appropriate active region methods are executed. If there are no active regions and preemption is enabled, default mouse actions are executed.
You cannot read from a mouse input stream unless the Window Tool Kit has been initialized. - 3.3.1 - Mouse documentation
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