Every man reaches a point in his life, when he needs to... click on specified point in window!

Here is my proposal for enhancing UI module with such a functionality:
' -- Win32
Begin Const
  %MouseEventF_LeftDown = &H2 
  %MouseEventF_LeftUp   = &H4 
End Const
Declare Sub mouse_event Lib "user32" Alias "mouse_event" (ByVal dwFlags As Long, ByVal dx As Long, ByVal dy As Long, ByVal cButtons As Long, ByVal dwExtraInfo As Long)

' -- Functions
Function Win_ClickAt( hWnd As DWord, x As Long, y As Long )

  Win_SetForeground(hWnd)
  
  Dim clickPosition As POINTAPI
  clickPosition.x = x
  clickPosition.y = y
  
  Win_ClientToScreen(hWnd, clickPosition)
  Win_SetCursorPos(clickPosition.x, clickPosition.y)
  mouse_event(%MouseEventF_LeftDown, 0, 0, 0, 0)
  mouse_event(%MouseEventF_LeftUp, 0, 0, 0, 0)  
  
End Function

Petr