PUBLIC objForm
objForm = CreateObject("TForm")
objForm.Visible = .T.
 
DEFINE CLASS TForm As Form
    Width=400
    Height=200
    Autocenter=.T.
 
PROCEDURE  Load
    THIS.decl
 
PROCEDURE  MouseDown
LPARAMETERS nButton, nShift, nXCoord, nYCoord
 
    * testing the mouse key state
    IF nButton <> 1
        RETURN
    ENDIF
 
    LOCAL lcCursorPos, hWindow
 
    * window handle for this form
    hWindow = GetFocus()
 
    * reading cursor position
    lcCursorPos = Repli(Chr(0), 8)
    = GetCursorPos(lcCursorPos)
 
    * Attention: at the next line the execution is stopped until
    * the mouse button released or the cursor moved out 
    * the drag-free rectangle centered on the current cursor position
    * with sides defined by the system
 
    * the width and height of this rectangle returned by the GetSystemMetrics 
    * function called with the correspondent SM_CXDRAG or SM_CYDRAG parameters
 
    IF DragDetect(hWindow, @lcCursorPos) <> 0
    * user moved the mouse outside of the drag rectangle 
    * while holding down the left button 
        ACTI SCREEN
        ? "Drag detected"
    ELSE
        ACTI SCREEN
        ? "Mouse key released without dragging"
    ENDIF
 
PROCEDURE  decl
    DECLARE INTEGER GetFocus IN user32
    DECLARE INTEGER GetCursorPos IN user32 STRING @lpPoint
 
    DECLARE INTEGER DragDetect IN user32;
        INTEGER hwnd, STRING @pt
ENDDEFINE