class

Tryst::NotViewableError

Inherits Exception < Reference < Object

Raised by Interp#simulate_event when its target window isn't viewable, which Tk's event generate answers by silently delivering nothing at all. Not a TclError, for the same reason WrongThreadError isn't: this is a precondition checked before Tcl is asked to do anything, not an error Tcl reported - Tcl reports no error here, which is the whole problem. See Interp#ensure_viewable!.