Gentoo version could bump to 0.3.7 the 0.4.2 is fltk2.
Done, a straight bump worked. Did not add 0.4.2 as it is only useful if fltk-2 is installed but fltk-2 is not in portage as far as I could see. Reopen if I am wrong and 0.4.2 provides some additional features, website says there are none. Thanks