The standard QSplitter works in only one direction (horizontal or vertical). If I understand your question correctly, what you are asking for is a grid splitter that works in both directions at the same time - that is, the splitter divides the space into 4 rectangles, and you can resize the rectangles by grabbing either the vertical bar, horizontal bar, or intersection of the two to resize all 4 windows at the same time.

There is an old thread here which discusses this, and maybe you can use the idea there to implement what you want.

There is also a post on linux-apps.com that might help. Also check the inqlude web site.