internationalizationkeyboardmacos
So it seems you have an either/or choice for the character accent menu or normal press-and-hold for key repeat behaviour.
Surely it's possible to have press and hold bring up the Character Picker accent menu, then – after a set delay – start repeating? Is there any way to enable this behaviour?
Some keyboard layouts (like Finnish, but not Danish) have a normal backtick under ⌥⇧´, so for example ⌃⌥⇧´ opens the console in Sublime Text.
If you don't want to switch to another keyboard layout, you can use Ukelele to modify the Danish layout. See this question.
The "Character Accent Menu" settings can be adjusted under:
System preferences -> Keyboard -> Delay Until Repeat
If you reduce this time, it's the fastest way to insert any accents in my experience. Setting the initial key repeat rate is the same as setting the time for the character accent menu to appear. With this solution, there is no need to change to international keyboards etc (see the other answers). see here.
If you set it to the minimum value, the delay will be 15 ms, which should be quite fast. However, there seems to be an actual delay of about 300 ms until the menu appears (maybe displaying the menu takes a while? Don't know).
There's people using scripts to set the delay from 15 to 1 ms, but I'm not sure whether this helps: see here: github.com/mathiasbynens/dotfiles/blob/master/.macos, the relevant parameter is InitialKeyRepeat
Best Answer
OK I think I finally understood what you want, and that is not possible.
Holding a key will bring up that character accents.
But you do not want to pick one you only want to have the pressed key repeat.
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So to do that you need following command in Terminal to enable it.
Since the keyboard is initialized during the boot cycle, you need to restart for it to take effect.
To set it back just use
Trueat the end instead of false.Unfortunately that will disable the "Accents" pop up since those 2 functions are conflicting.
Writing a Script that switches the function for the press and hold is useless since you would need to restart anyway.