EventHandler—Wolfram Mathematica 9 Documentation

Details and Options Details and Options

	"MouseClicked"	mouse clicked without moving
	{"MouseClicked",i}	mouse button i clicked without moving
	"MouseDown"	primary mouse button depressed
	{"MouseDown",i}	mouse button i depressed
	"MouseDragged"	mouse moving with primary button depressed
	{"MouseDragged",i}	mouse moving with button i depressed
	"MouseMoved"	mouse moves in the region defined by expr
	"MouseUp"	primary mouse button released
	{"MouseUp",i}	mouse button i released

For mouse events, EventHandler[expr, ...] handles events for which the mouse is within the rectangular region defined by the display of expr.
Standard keyboard-related event specifications include:

	"KeyDown"	any key on the keyboard depressed
	{"KeyDown","x"}	key x depressed
	"ReturnKeyDown"	Return or Enter key depressed
	"EscapeKeyDown"	Esc key depressed
	"LeftArrowKeyDown"	left arrow key depressed
	"RightArrowKeyDown"	right arrow key depressed
	"UpArrowKeyDown"	up arrow key depressed
	"DownArrowKeyDown"	down arrow key depressed

Standard interface events include:
{"MenuCommand","name"} menu command with specified name chosen

"WindowClose" closing of window requested
If functions like MousePosition or CurrentValue are evaluated in a particular , the values they give are those associated with the event that triggered that .
When EventHandler expressions are nested, events are by default shared by all the expressions, with the innermost expression operating first on a particular event.
The following options can be given:
PassEventsDown Automatic whether to pass events to inner event handlers

PassEventsUp True whether to pass events to outer event handlers
With the default setting PassEventsDown->Automatic, events handled by an EventHandler are not also passed to built-in event handlers in the Mathematica front end.