Keyboard Layout

I use Caps Lock to switch between US standard and my personal US umlaut layout.

Linux Ubuntu 16.04

1. We need to deactivate the standard function of Caps Lock:

sudo apt-get install gnome-tweak-tool

2. Go to "Typing" -> "Caps Lock key behavior" -> "Caps Lock is disabled"
3. Copy the following file to /usr/share/X11/xkb/symbols:

/////////////////////////////////////////////////////////////////////////////////
//
// Generated keyboard layout file with the Keyboard Layout Editor.
// For more about the software, see http://code.google.com/p/keyboardlayouteditor
//

default partial alphanumeric_keys
xkb_symbols "ap"
{
	name[Group1] = "English (US, Umlauts)";
	include "us(basic)"
	key <AC10> { [     odiaeresis,     Odiaeresis                                 ] }; // ö Ö 
	key <AC11> { [     adiaeresis,     Adiaeresis                                 ] }; // ä Ä 
	key <AD11> { [     udiaeresis,     Udiaeresis                                 ] }; // ü  
	
	include "level3(ralt_switch)"
};

4. Now we just need to configure Ubuntu to switch the keyboard layout by pressing Caps Lock. System Settings -> Keyboard -> Shortccuts -> Typing -> Switch to next source -> Now press the "Caps Lock" key.

Troubleshooting

If for some reason you sometimes have troubles switching the input source, you might have the problem that the system "forgets" your way to switch the source. So we can put the following code into the /etc/rc.local

dconf write /org/gnome/desktop/wm/keybindings/switch-input-source "['0xffffff']"

Now we just need to enable the rc-local.service:

sudo systemctl enable rc-local.service

If this also does not work. It is because the /etc/rc.local is not executed. Try using crontab:

sudo crontab -e

Then add the following to the end of the file: /etc/rc.local

Windows 10

1. Control Panel -> Clock, Language, and Region -> Language -> Advanced settings -> Change language bar hot keys -> Advanced Key Settings
2. Choose "Press the SHIFT key" to turn off Caps Lock. All key sequences for the Action can be (none).
3. Download the keyla program: 'http://www.softpedia.com/get/Office-tools/Other-Office-Tools/Keyla.shtml'
4. Go to Common -> Shortcut to switch layout -> Caps Lock