there are two small bugs in SimpleGraph.
First of them - still the bug described in this post: http://www.delphiarea.com/forum/viewtopic.php?t=244
. You can see black lines when zoom is >=350%. Just increase zoom using toolbar button for few times and the black lines will appear on right/bottom of the drawing area.
Another bug can bee seen on the screenshots. Looks like SimpleGraph incorrectly recalculates max values for scroll bars in zoom mode.
Create any node, press zoom button in order for scroll bars to appear and click anywhere in the SimpleGraph's drawing area. Max values for scroll bars will be recalculated although there is no need for this.