<ITEM> <<setGrab(global:B)>> : Sets a grab on the widget. If <<B>> is <<true>> then the grab is global, otherwise it is local (<<B>> false by default). If a grab was already in effect for this application then it is automatically released. If there is already a grab on the widget and it has the same global/local form as the requested grab, then the command does nothing. Local grab affects only the grabbing application: events will
be reported to other applications as if the grab had never occurred. A global grab
locks out all applications on the screen, so that only the given subtree of the grabbing application will be
sensitive to pointer events (mouse button presses, mouse button releases, pointer motions, window entries, and
window exits). During global grabs the window manager will not receive pointer events either. Warning : whe a grab is set, it is define for the whole Oz process so that it will prevent the user to do input to other windows as well. Moreover a grab is still effective even if the window that contains the grabbed widgets is hidden. <<B>> must be a boolean.
