[plt-scheme] clicking in an editor window

Matthew Flatt wrote:

> An alternative is to get the editor's keymap, and then install an
> action for "leftbutton", etc.: [...]

> Instead of `semaphore-wait', you can use `yield', which handles GUI
> events while it waits for the given synchronized object to be ready.
> I think that's probably the right approach in this case.

Both of these are simple to understand and implement (literally four 
lines of added/changed code), I have the desired behaviour, and I have 
learned something about the greater context. Many thanks for the prompt 
reply. --PR