OCC offset

After "geo" from #cam mentioned using Open CASCADE's Test Harness and gave me an example, I produced these offsets, which look promising for pocketing with a permissive license. It seemed to produce the offsets very fast.

flyout toolbars again

I changed the flyout toolbars to use a popup window with a toolbar in it, instead of the popup menu I was using before. The tooltips don't seem to be working on the Windows version, though.

Graduated Background

I added a graduated background.
Feel free to suggest some better default colors.
The default is for the color to change from top to bottom, but I have added modes for single color, left to right shaded and four corner color setting.

Flyout toolbars

I've added fly-outs menu to toolbars in HeeksCAD. Currently you have to press the little arrow button to get the popup menu. Then you have to click again on the menu item. I want it to work with a click and drag, rather than two clicks. Also, I want to get rid of the little arrow button and have click and drag work on the main toolbar button. Also, I want the button on the toolbar to change to the last used tool from the drop-down. I can't work out how to change the tool bitmap, though.