Redesigning the coontrolbar? Particulary into a sidebar? Want to know how to get rid of that nasty black space?
Well, you can't, and admitting it is the first step to a solution.
The best you can do, for now (I am STILL researching it), is sacrafice your minimize controlbar ability for an off/on button on that black space, it may not seem like a solution but when you've spent alot of work on your nice new spiffing sidebar its actually quite a relief as the only inconvenience is having to click an extra button once every game, oh and not be able to minimise the controlbar (use F9 anyway you dolt!

).
Here's how.
Get your hands on a 'big' format extractor, open up windows.big and extract that ControlBar.wnd.
Next, open it up in notepad.
What we want to do is make the controlbar not move an inch after its been told to minimise while the black space will just dissapear, the distance the controlbar minimises is proportional to the co-ordinates of the main window, the ControlBarParent.
The exact co-ordinates to prevent the controlbar moving anywhere are 0 540, but here's the catch, no buttons work unless they're within this window, so we have to modify the controlbar.wnd code a little so that we'll have an extra window that will enable the use of all the buttons.
It's quite simple really, in notepad, change the first 'UPPERLEFT' values to '0 540' and then from the top of the file copy the text from the first mention of 'WINDOW' down to the last line before the first mention of 'CHILD'. Just before this word 'CHILD' now insert an 'END' and then paste the code after this 'END' word. In this copied code, delete the 'ControlBarParent' part of it's name leaving just 'ControlBar.wnd:' and then give that window the dimentions you want so that it covers all your buttons, frankly 'UPPERLEFT: 0 0' and 'BOTTOMRIGHT: 800 600' would work for all cases.
To put it into effect, situate your ControlBar.wnd within the folder 'Windows' within your Generals directory, or in a BIG file with its proper name.
And there you are, game will start with that usual annoying black space but press the minimize button and hey presto it's gone!
Even if this doesn't suit you as you are too fussy having to press an extra button, I'd recommend doing it as its a step in the right direction, who know's somebody may find a way to enable the minimise button from the start and all you have to do then is situate the minimise button off the view area and nobody would be the wiser!