In windows (and also linux) when dragging an object is "glued" to the mousecursor. no matter how fast you move it stays on.

How is this achieved ? when updating my object with mouse.dx and mouse.dy there is always some lag between mouse position and object position.

any ideas ?

True, but the windows ( in windows and in linux) stick nicely to the mousecursor when you drag them. So there has to be another way.

First, you need to be more specific. What OS are you using? Are you using Allegro to draw a system cursor? Or are you drawing the mouse yourself? How are you monitoring the mouse position? On Windows, you can set a callback process that can process mouse moves.

I'm currently making a missile defense game and I have zero lag with the mouse. I draw my own pointer. All I do is respond to ALLEGRO_EVENT_MOUSE_AXES events.

You should show code if possible.

I did finished my own GUI system for the engine I'm creating. I wrote it in Object Pascal, I'm drawing the mouse cursor by myself and I haven't such "lag" drawing the mouse.

My system is quite complex (mouse is an independent object and cursor is managed by GUI and everything is decoupled...) but in short is similar to this:

PROCEDURE RenderMouseCursor
VAR
    State: ALLEGRO_MOUSE_STATE;
BEGIN
    al_get_mouse_state (State);
    al_draw_bitmap (
      MousCursorBmp,
      MouseOffsetX + State.X, MouseOffsetY + State.Y,
      0
    )
END;