Hi. Icons in OpenGoo are determined by the file's mime type, not the extension. Though I just made the changes so that in next release you can add an icon according to the extension. For the moment you have to deal with the mime type.
Assuming that the mime type is 'application/dwg' (you may have to google it or look in the og_project_file_revisions database table), you have to do this:
1) Add an image for the file type that is 16x16 pixels in size to 'public/assets/themes/default/images/16x16/types' and name it 'application-dwg.png' (the general rule for the filename is: replace slashes with dashes). The format doesn't need to be PNG, it could be GIF, but I don't know if ICO would work.
2) Add an image for the file type that is 48x48 pixels in size to 'public/assets/themes/default/images/48x48/types' and name it 'application-dwg.png'
3) In file 'public/assets/themes/default/stylesheets/custom.css' (if this file doesn't exist create it) add a couple of CSS rule for the file type, like this:
.ico-application-dwg {
background-image: url(../images/16x16/types/application-dwg.png);
}
.ico-large-application-dwg {
background-image: url(../images/48x48/types/application-dwg.png);
}
4) When file extension is supported you will be able to add the following rules:
.ico-ext-dwg {
background-image: url(../images/16x16/types/dwg.png);
}
.ico-large-ext-dwg {
background-image: url(../images/48x48/types/dwg.png);
}
5) Refresh your browser