The split view is a basic feature of the Windows MDI (multi-document interface) and is only for deviding a view of 1 document into two parts to be able to see one part of a document and while editing in another part of the same document.
I will explain now how the Microsoft MDI features Tile Horizontal and Tile Vertical should be used if many documents are opened at once and only some of them should be tiled horizontally or vertically. This is a general description, not specifically for UltraEdit. You can use the same technique in MS Word, Adobe Reader, and other applications using the Windows MDI.
- Click on Window - Minimize All Windows.
- Locate now the document windows you want to tile horizontally or vertically and restore these windows, but don't maximize them. In UltraEdit you can do this very simple by clicking on the tab of the document in the open file tabs bar. In other applications you would need to use Window - Windows if you have so many files open at once that you can't find them easily on bottom of the main window.
- After restoring the windows of the documents (files) you want to tile horizontally or vertically, click on Window - Tile Horizontal or Tile Vertical. The Microsoft MDI functions recognize only not minimized windows and you will get what you want.
The Eclipse IDE feature you have described is really a very nice feature and therefore really worth to send it as feature request email to IDM.