WM_XBUTTONDBLCLK top-level constant
int
const WM_XBUTTONDBLCLK
Posted when the user double-clicks the first or second X button while the cursor is in the client area of a window. If the mouse is not captured, the message is posted to the window beneath the cursor. Otherwise, the message is posted to the window that has captured the mouse.
Implementation
const WM_XBUTTONDBLCLK = 0x020D;