Tested in Windows and Linux versions, Geany 1.32.
1. Have two or more files opened with Geany (not sure if with 1 also happens) 2. Go to Edit > Preferences > Editor 3. Check the first item in "Features" section; line adjustment. 4. This should make the lines not to be rendered beyond the right margin of the window, making them split into multiline (not actually adding a \n char, you know). It doesn't happen. 5. Close the Geany window. Reopen it. 6. The lines still are not displayed multiline (adjusted). 7. Close one file tab. Reopen the same file. 8. Lines are finally correctly rendered.
I think it'd be awesome to see the new preferences setting in effect in (4), although at least in (6) the lines should be correctly rendered.
Please, contact me if further details are needed. Thanks.