I installed the tangible t4 editor extension in vs2010 that gives some basic syntax colouring for t4 templates (.tt).
When I add a t4 template via the wizard it opens with syntax colouring.
After closing the file and double-clicking it opens again with syntax colouring.
After closing the file and using the 'open with' menu and choosing the default: 'automatic editor selection', it opens with xml file syntax colouring.
That's strange because I always assumed that double-click equals the default 'open with' menu item. Do you know what's going on?
The problem arises when one adds a t4 template without using the wizard - no syntax colouring.