Window Manager / Widgets

The callback mechanism offers users an event-driven system for windows and window objects (widgets). For nearly every possible event—such as touch input, drawing, or key input—the window manager determines which window is affected (e.g., a touch input within a window’s area) and sends a message to that window. Within the callback function, the user can react to these messages and define the appropriate response.

For example, when a window becomes invalid, the window manager sends a paint message (WM_PAINT) to trigger a repaint. The user can then respond to this paint message by calling the appropriate drawing functions to define the appearance of the window.

This mechanism gives the user full control over the behavior and appearance of each window. This can easily be achieved by assigning a custom callback function.

The Window Manager includes widgets (window objects) that provide the user with a wide range of elements such as buttons, progress bars, edit boxes, spinboxes, and more. These widgets are windows with predefined behavior—for example, a button responds to touch input.

Since widgets are still windows, they can be configured just like any other window, simply by assigning a custom callback function.