Alt code with letter + not working

Solution 1:

Windows does support Unicode sequences, but you'll need to make an adjustment as described on Wikipedia:

[...] a user must set or create the registry key HKCU\Control Panel\Input Method\EnableHexNumpad with type REG_SZ to value 1 and reboot (logging out and logging back in is sufficient). Once the registry key is set, the following method can be used to enter Unicode codepoints:

Hold Alt and type the + key on the numeric keypad, then type the hexadecimal number (using the numeric keypad for digits 0-9 and the normal keys for a-f), then release Alt.

For example, Alt++11b will produce "ě" (e with caron).