Routines (alphabetical) > Object Classes > Graphics Object Classes > IDLgrWindow::OnMouseDown

# IDLgrWindow::OnMouseDown

Syntax | Arguments | Keywords | Version History

The IDLgrWindow::OnMouseDown procedure method handles notification from the window that a mouse-down event has occurred.

Note: This method is only useful in conjunction with the Export Bridge. The method is only a stub and provides no functionality. In your subclass of IDLgrWindow, you should override this method to provide your own functionality. Your method will be automatically called by the Export Bridge. For more information, see "Exporting Drawable Objects"(Chapter 11, IDL Connectivity Bridges in the `help/pdf` directory of your IDL installation).

## Syntax

Obj->[IDLgrWindow::]OnMouseDown, X, Y, ButtonMask, Modifiers, NumClicks

## Arguments

### X

A long integer representing the x-location (in device coordinates) of the mouse event.

### Y

A long integer representing the y-location (in device coordinates) of the mouse event.

### ButtonMask

An integer containing a bitwise mask indicating which of the left, center, or right mouse button was pressed:

Bitmask | Mouse Button
1 | Left
2 | Middle
4 | Right

### Modifiers

A long integer containing a bitwise mask indicating which modifier keys are active at the time the mouse button is pressed. If a bit is zero, the key is up; if the bit is set, the key is pressed. The following table describes the bits in this bitmask:

Bit | Value | Modifier Key
0 | 1 | Shift
1 | 2 | Control
2 | 4 | Caps Lock
3 | 8 | Alt

### NumClicks

An integer indicating the number of times the mouse button was clicked.

## Keywords

None

## Version History

6.3 | Introduced