Excellent.  :)
One small thing: When you quick-edit a chart and change nothing but its chart name, there is no save-prompt when closing the builder. But that's minor, not really important.

To test it on a high-dpi screen, I have to wait for the weekend. Will let you know should I notice any issues.

Thanks a ton for implementing everything so quickly.  :up: :Thmbsup:

@ cranioscopical,
glad you spotted this. I don't have access to a high dpi screen right now, but will definitely try it later this week to see if I can reproduce it.

@ hamradio,
the latest beta works like a charm for me on my 1920x1200 screen. Charts are easy to edit, Always on top is correctly kept up from the main window. The button on top right is a welcome additional bonus feature.

Nothing I could wish for at this time, in terms of features and ease of operation.  :) :)

Terrific, looks very promising indeed.  :-*  And much sooner than I had possibly hoped for.

One last thing:
Loading/switching charts were much faster if we could have an entry "Open Custom Chart" right in the Charts main menu. Below or above "Open Temporary" for instance.

Your alphabetical flyouts are well-intended. I can imagine them being very useful for organized folks who maintain a large database of clients/ websites. Me, I juggle 10-12 charts that I mainly use.
Too many to remember what Alt-shortcut goes with what chart, so I click on "Explore Custom Directory" to see what I have, then back again via the hover-flyouts to wait for the letters of the alphabet, only to be reminded that these are not tied to the file names I just googled via "Explore Custom Directory". I'd have to open them one by one and prefix their chart-name (not file name) to see them all at one quick glance under 1_ oder _underscore flyouts.

For users like me, a classical open-dialog would be much faster. Easy enough to spot the right chart at one glance, possibly creating sub-directories if necessary.

Talking subfolders, is there a reason why the Open-dialog of the ChartBuilder jumps to the main folder? Charts you keep there won't show up in the charts flyouts anyway, so why not open the dialog directly into \custom where they live?

Looking forward to the update. Thanks again.