/* TheGood
How to detect doubleclicks in ListBox
*/

Gui, Add, ListBox, hwndhLB, This is a listbox item
OnMessage(515, "OnDblClick")   ;Intercept WM_LBUTTONDBLCLK notifications
Gui, Show
Return

GuiClose:
ExitApp

OnDblClick(wParam, lParam, msg, hwnd) {
   
   ;Make the var global so that we can access it
   Global hLB
   
   ;Make sure the notification comes from the listbox
   If (hwnd = hLB) {
      
      ;Get item count. 395 = LB_GETCOUNT
      SendMessage 395, 0, 0,, ahk_id %hwnd%
      iCount := ErrorLevel
      
      ;Check for error
      If (ErrorLevel = 0xFFFFFFFF)
         Return
      
      ;Get the bottom edge of the last item. 408 = LB_GETITEMRECT
      VarSetCapacity(uRect, 16, 0)
      SendMessage 408, iCount - 1, &uRect,, ahk_id %hLB%   ;%
      iBottomEdge := (ErrorLevel <> 0xFFFFFFFF) ? NumGet(uRect, 12) : 0
      
      ;Extract the Y coordinate of the mouse click from lParam (high word)
      iY := (lParam - Mod(lParam, 0x10000)) / 0x10000
      
      ;Check if mouse click is under or over bottom edge
      If (iY > iBottomEdge)
         GoSub ListBoxDoubleClickOffItem      ;The dblclick was off an item
      Else
         GoSub ListBoxDoubleClickOnItem      ;The dblclick was on an item
      
   }
}

ListBoxDoubleClickOnItem:
   MsgBox You double-clicked on an item!
Return

ListBoxDoubleClickOffItem:
   MsgBox You double-clicked off an item!
Return