I love it. The dragging of black holes could be improved:

* The black hole is not moved until the cursor has moved more than five pixels.

* The first time the black hole moves in the dragging process, it moves more than one pixel, afterwards one. So it is a small jump and then it moves smooth.

* The cursor icon changes to the drag symbol only after the mouse has already moved five pixels, not as soon as the mouse button is hold down.

* When the mouse is outside the draggable zone, but still in the game window, the black hole is not dragged along the border.