I've implemented an easy plugin for Sublime Text 2. It's my first plugin and I hope, that it helps some people who haven't implemented it for themself.
It's called toggle-readonly and allows you to toggle the active view/buffer as readonly. It doesn't change the file parameters in the file system it only changes the read only property of the buffer.
So it's a very small and handy plugin which calls:
You can set this with a mouse-click on the buffer-tab, the open file menu and on the edit-area of the buffer itself.
Unfortunetaly it's not available via the Package Control yet, I'll change that later...
You can download it here: https://github.com/AxxL/sublime-toggle-readonly
What I would like to have is a change of the buffer-tab. Some change of the buffer-text or a change of the color of the tab. Maybe later. Credits: Some forum post where this topic was discussed. g.