I have an 'auto-complete list' and basic function 'help tooltip' mechanisms working nicely.
The current code highlighting is just the default Visual Basic support in the control, but adding more won't be very hard at all.
The 'window' is just a bunch of DesktopX objects and graphics, no animations but the buttons etc. all do what they are supposed to.
Interestingly the ActiveX control I've used has many functions I can't make use of as they are intended for proper Visual Basic interfacing - one in particular is controlling which lines are rendered, which I could use to create collapsible sections.
Also some apparent bugs in the control which I've had to script inelegant (but functional) workarounds for as I don't have source code (and wouldn't know how to edit it anyway).
To add:
- function 'jump list' (to jump to a Sub or Function) without having to scroll through the script via a drop list.
- rather than 'tabs' for each script, a treeview of DesktopX objects, clicking nodes to show the script.
- compiling a bunch of xml entries for various vbScript object models for the 'intellisense' - vbsEdit (mentioned by c242) will probably help me out there as it already has a comprehensive list.
- object variable typing - this is so if you create a variable to hold e.g. a FileSystemObject, the 'intellisense' will know to display FileSystemObject information correctly.
WIP-shot: 
