Just in case somebody has the same problem, i found a good workaround (at least for linux-users).
the problem seems to be, that for some keyboardlayouts (for example swisslayout), you need to press the right ctrl key and the key next to backspace…after that you need to press space to generate the tilde-symbol (~). This seems not to work with the defold editor.
workaround:
i just made acopy of the swisskeyboardlayoutfile and changed a key, which i never use to the (~). if you want to change a keyboard layout, the name of the ~-symbol is asciitilde.
greetings
chris