From Original War Support Wiki
Tutorials -> Devmode
Dev mode allows you to modify the colours used in the Alien, American, Russian and Arabian interfaces as well as the fonts used. Note that on 1.07 and below the background of the windows below is black meaning that the "Alien" interface's buttons will look like they have no text (as the text is also black). See Parameters for a full list of Parameters Original War handles as well as how to use them.
Note: before you try and use the 2 features of devmode you need to have a mod loaded. If you try and change colours when no mod is loaded then you may get errors.
Pressing CTRL+F5 when devmode is active will bring up the screen to change which interface to use, selecting another interface will only change the text's colours and fonts to the selected interfaces ones.
Interface Colour Selector
Pressing CTRL + F8 when devmode is active will bring up the screen which allows you to modify the current interface's (See CTRL+F5 for the current one) colours and fonts. The preview checkbox will make any changes you make visible on the interface in the background. The corners allow you to move the window so you can see the changes you make in the interface behind the window.
Note: you need to have Interface\UIColors.txt present in your Mod Directory which you can extract from Data1.owp using PakView.