A modal dialog temporarily disables its main application window while the modal dialog is visible. All keyboard and pointer events get ignored by the main application window if at least one of its modal dialogs is visible. Hiding (or completely destroying) all of its modal dialogs restores normal keyboard and pointer event processing. On most display servers the main application window is visibly dimmed, or shown in washed-out colors to indicate that it's disabled by an active modal dialog.

Modeless dialogs have no effect on the dialog's main window. Both the dialog itself and the main window continue to process keyborad and pointer events normally, all the time.

A modal dialog created from another dialog disables only the dialog its created from, and has no effect on the main window. Modal dialogs block keyboard and pointer events only from the immediate window or the dialog they get created from.