void show(control c); /* make a control visible to user */ void hide(control c); /* hide a control from the user */ int isvisible(control c); /* is this control visible? */
The show and hide functions make a control visible or invisible on its parent window, and isvisible returns a non-zero value if the corresponding control would be visible if unobscured.
By default, controls are visible when they are created. Visibility is the quality of whether the control should be drawn if it is not obscured, not whether the control is currently unobscured.
A control might be visible, even if its parent window is not. Every object has its own visibility state, which is separate to every other object's state.