allow for arbitrary exit keys to exit app_main_loop

[mdpetters]

This change allows the use of any key when exiting the main loop. For example:

app_main_loop(exitkey = Keystroke(Int32(27), "\e", :esc, false, false, false))

uses ESC as the exit key. It is handled as a keyword, so the default "F1" exit behavior of

app_main_loop()

is unchanged.

[ronisbr]

Hi @mdpetters !

Awesome! However, let me provide a suggestion. I think it will be cumbersome to ask for the user to define the structure Keystroke for the key they want (notice that it is necessary to correctly define all the fields). What if we create a function keyword called something like check_exit_keystroke. This function will have the following API:

check_exit_keystroke(k::Keystroke) -> Bool

If it returns true, the loop ends. Hence, the user can do something like this:

app_main_loop(; check_exit_keystroke = (k) -> k.ktype == :esc)

To exit on ESC for example.

What do you think?

[mdpetters]

I think it makes sense to keep it simple along the lines you suggest. However, it would be nice to have complete keystroke support if needed. The updated code can check for equality of either the entire keystroke or just the ktype. This way the user has the choice.

[ronisbr]

Awesome! Thanks!