change colouring scheme for a file extension?
There is not yet a graphical UI to handle this but it can be done nonetheless by editing the syntaxcolouring.xml file.
You can load the file in Ellié Computing Merge and edit it (use XML pretty-printing feature to get it in a better shape).
Each /syntax-colouring/lexer/association node contains an extensions attribute, you can add or change these extensions. For example, if you would prefer Hypertext colouring scheme for .ASP file, you can do that:
If you want another colour or change bold/normal font for a style, you can have a look to the style nodes under a scheme (lexer nodes). The notation is the HTML notation (i.e. a font tag, with color and bgcolor attributes, use "bold=yes" for bold, italic="yes" for italic). Note that background colours are ignored in differentiation mode, so as not to interfer with differences background colours.
Ellié Computing Merge takes its syntax colouring scheme in priority from user's folder (search mergeconfig*.xml and put your modified copy of syntaxcolouring.xml in the same directory), then from the installation directory if user's version was not found. Doing this will prevent the replacement of your modifications with the base version during next upgrade.