Ordering of command completions

[Tom]

Just a quick thought: various modes have lots of keybindings and
often I use M-x to invoke commands of unfamiliar or rarely used
modes, because I don't always know the relevant keybindings. Of
course, I can use the prefix of the mode when completing, but I
may not know it and it may not be obvious depending on the
mode. It occured to me that M-x, when showing completions, could
list command matches from the current major mode first, then from
the minor modes and then the rest of the commands.

It could improve M-x usability and help with the discoverability
of commands in the active modes, because commands relevant to the
current context would be listed first, instead of everything in a
huge alphabetical list.