Kljúfa
Divides the current window at the top left corner of the active cell.
You can also use the mouse to split the window horizontally or vertically. To do this, drag the thick black line located directly above the vertical scrollbar or directly to the right of the horizontal scrollbar into the window. A thick black line will show where the window is split.
A split window has its own scrollbars in each partial section; by contrast, fixed window sections are not scrollable.