Occurs when the user presses a mouse button.
TXRulerBar.MouseDown(Button, Shift, X, Y)
Informs which button is pressed. Possible values are the following:
Informs about the state of the SHIFT, CTRL and ALT keys at the time of the event. It is the sum of one or more of the following values:
Specifies the current location of the mouse pointer. The coordinates are relative to the upper-left corner of the ruler bar.