Splitter control reworked

[Biterider]

Hi
I recently found that the implementation of the Splitter control did not work properly on Win10. The reason was that when drawing on the desktop something changed. Some regions were restored to the original background without reason. In some regions, the original background has been restored for no reason.

I've looked into this issue in more detail, recoded the control and added a new feature. I call it FlipBox. When you hover with the mouse over the splitter or press the right mouse button, the FlipBox is displayed, allowing you to jump to the right/left limit or the splitter last middle position. 

Serialization is also updated accordingly to store and restore the application state.

I tested it on Win10/7 64 bit. Attached is the binary.

Regards, Biterider