FWIW,
soso news
I have implemented rudimentary scrolling, and I have it integrated into (checkout of) CB wxpropgrid_debugger branch, using the GDBWatch entities. (I didn't actually get scrolling implemented in the demo, because it was going to require too much throw away framework for data structures, since a specific one was going to need to be supported. Hence the move to integration into CB branch.)
bad news
It doesn't work nearly as smoothly integrated into the whole as it seemed to in the much smaller demo program, even after a number of "hacks" attempting to address the various visual, and some not-so-visual, issues I have encountered.
(obfuscated, others) Do you want me to bother attempting to post a patch in its current state. (The code is quite dirty at the moment, as it has my "running history" of the various things I've tried. It only contains code added to gdb_tipwindow.<cpp,h>, (all classes lifted from the demo, not mods to existing tipwindow stuff), and slight change to gdb_commands.h to invoke it. [well, excepting all the update.bat files that are not winxp sp2 compatible, at least in terms of line-endings, that I changed when I originally obtained and built the branch])
I am currently a bit frustrated, but have not yet given up entirely. I'm not sure when that might change, based on available resources and other priorities.
ps - it currently does have borders around the frames, as with default (editor) colors on my winxp mach, it was very hard to see without them. This is currently a minor difference of a flag passed to the underlying frame-descendant constructors.