helm-themes loads the themes present in custom-load-themes which are coming from custom-theme-load-path (as per C-h f helps)
After installing themes mega-pack, the list is the following :
Available Custom Themes: [ ] spacemacs-dark -- Spacemacs theme, the dark version [X] spacemacs-light -- Spacemacs theme, the light version [ ] adwaita -- Face colors similar to the default theme of Gnome 3 (Adwaita). [ ] deeper-blue -- Face colors using a deep blue background. [ ] dichromacy -- Face colors suitable for red/green color-blind users. [ ] leuven -- Face colors with a light background. [ ] light-blue -- Face colors utilizing a light blue background. [ ] manoj-dark -- Very high contrast faces with a black background. [ ] misterioso -- Predominantly blue/cyan faces on a dark cyan background. [ ] tango-dark -- Face colors using the Tango palette (dark background). [ ] tango -- Face colors using the Tango palette (light background). [ ] tsdh-dark -- A dark theme used and created by Tassilo Horn. [ ] tsdh-light -- A light Emacs theme. [ ] wheatgrass -- High-contrast green/blue/brown faces on a black background. [ ] whiteboard -- Face colors similar to markers on a whiteboard. [ ] wombat -- Medium-contrast faces with a dark gray background. How is it possible to have access to all the other themes available here http://themegallery.robdor.com/
Are they not in the mega pack ?