[TRMW]
flatten_dialog=0
This setting was introduced in 4.621, but has changed considerably in 4.622.
If 1, maps that have a 3D border and a title bar are shown with a flattened border similar to the border used in Windows XP.
If 0 (maps with a 3D border and title bar are shown with a 3D effect.
If 0 (maps with a 3D border and title bar are shown with a 3D effect, as "normal".
If 1, maps that have a 3D border and a title bar are shown with an XP window border, and the borders of 3D edit controls are also changed to match those of XP, but only if a Windows XP theme is in effect.
If 2, maps that have a 3D border and a title bar are shown with an XP window border if there is an XP theme, or a fat flattened border (reminiscent of Windows 3.x) otherwise. The borders of 3D edit controls are also changed to match those of XP, if there is a Windows XP theme is in effect, or are flattened anyway otherwise.
You should note, that when there is an XP theme and flatten_dialog is non zero, you cannot be sure of the exact appearance of the map. For example there are various shareware programs available that provide new themes beyond the MS supplied themes.