I used to have that "tiny windows" too...
You can try using OpenSetup to fix it!
If you don't have that?
http://nn.nachtwolke.com/dev/opensetup/
Download and put in your heRO's folder.
1) In bottom left: first click on REG. Choose a Resolution you like, click Apply.
2) Then click on LUA, choose a Resolution, click either OK or Apply.
This way you'll have edited both the registry and .lua file, should solve tiny windows problem!