You could use:
+ MouseKeyboard: On Left Clicked on Sprite
-> Sprite: Set 'drag' to 2
+ Sprite: Value 'drag' Equal to 2
+ MouseKeyboard: Left mouse button is down
-> Sprite: Set position to MouseX, MouseY
+ MouseKeyboard: On Left mouse button released
-> Sprite: Set 'drag' to 1
sample cap
<img src="smileys/smiley1.gif" border="0" align="middle">