I can't get that to work

. When I try having it in a static block, it says it can't find the field, and when I try passing it as VM arguments it can't find the main class. This might very likely be a problem on my end since I'm not very good with this aspect of java developing.
Anyway, since setClipMouseCoordinatesToWindow() should already do what I understand org.lwjgl.input.Mouse.allowNegativeMouseCoords is meant to do and more, it probably isn't enough.
I checked the values for X, DX, Y and DY with the following lines everytime a mouse event occured:
System.out.println("X = " + Mouse.getEventX() + " Y = " + Mouse.getEventY());
System.out.println("DX = " + Mouse.getEventDX() + " DY = " + Mouse.getEventDY());
When moving the mouse below and to the left of the window, X and Y are both 0, but DX and DY are not. Again, it only behaves like this when either mouse button is held down since it doesn't generate events otherwise.