Menu: Catalog -> Settings will open the Settings dialog. On the Project Info tab you find a Plural Forms edit at the bottom. Just put a plural form in here.
nplurals=2; plural=n != 1;
That was german, two plural forms.
nplurals=3; plural=(n%10==1 && n%100!=11) ? 0 : ((n%10>=2 && n%10<=4 && (n%100<10 || n%100>=20)) ? 1 : 2);
That was russian, three plural forms.
Just press the OK button and Poedit will reflect the changes on entries offering plural forms:
(Do not mind that the russian translation is missing, we actually figured that out so that the translator can use Poedit to start translating.)
Hopefully this will help others as well to get this running. When you close the file you might get an error-message. So it’s wisely to just close the file after the change of the setting and re-open it again. It then should work properly.
The good thing is with this little setting you can get the .pot files to work that you can download in your plugins admin section on wordpress.org if you’re a plugin author. Just browse to your plugins address and add admin at the end:
You can then obtain a .pot file there, the section is named Generate POT file.