Windows 10 – Fix Alt+Space Keyboard Shortcut Not Working

You can configure your shortcuts to free the Alt+Space combination in Opera.

1. From the main menu, select Settings.
2. Click Browser on the sidebar.
3. Under Shortcuts, click the Configure Shortcuts button.

I view it as a behavior which can be called a defect from some viewpoint. I am not sure if there is any solution to that. Maybe you can try with Slovak keyboard layout, it has all the German characters (placed differently, and for example ö might require pressing dead key AltGr+-, o but they are all there) because I do not remember any issues with AltGr on that keyboard layout.

Another workaround is to click accessibility icon on login screen (or press Win+U for the same action) and enable On-screen keyboard from displayed menu. Then you can access desired characters by clicking on that on-screen keyboard.