Well, in fact, I solved the problem myself by using the -window tag after the command line in my OpFP Shortcut. So the starting command is operationflashpoint.exe -window .
However, there is a NEW problem. Or, it's not a terrible one, but a problem still; there are two mouse cursors on the screen simultaneously, moving at different speeds. I don't mind the windows cursor being on-screen when I use the game cursor, but the problem is that when I press my mouse button, it will primarily take any response from the windows pointer. So I'll have to keep both cursors on the same window simultaneously unless I want to skip to another program.
In the end, I can live with this if I use a full screen size window in the editor. And even like this, the editing work is a LOT better.