This is a quick and dirty guide to hacking your screen mode. This is not the right way to go about it. The proper thing to do would be to add a new menu item which allows you to select different screen modes. However I have been asked by several people how to change screen resolutions, and how to make your window fill the whole screen(rather than having part of it unused). So here it is, quick and to the point.

To change your actual screen resolution you will need to modify lines 308-309 in genvs.c. These lines read:

    CWidth = 640;
    CHeight = 480;

Simply change these values to the screen width and height desired. For example to go into 800x600 mode you would change these lines to:

    CWidth = 800;
    CHeight = 600;

Keep in mind, that your card must support whatever resolutions you try to go into.

If you try to run Gtest.exe with these changes you will notice a problem. The window does not fit the screen. That's okay though, the window never used the whole screen to begin with(it was not using the bottom 60 lines). To remedy this problem we need to open up client.c and go to lines 2002-2005, which look like the code below:

    Rect.Left = 0;
    Rect.Right = 639;
    Rect.Top = 0;
    Rect.Bottom = 479-60;

We need to change these values to fit our screen resolution. For example if we were still in 640x480 and wanted to use that lower 60 pixels we would simply modify line 2005 to look like this:

    Rect.Bottom = 479;

If we wish to change our resolution to 800x600 the following code snippet will do:

    Rect.Left = 0;
    Rect.Right = 799;
    Rect.Top = 0;
    Rect.Bottom = 599;

Enjoy.