Some applications installed in playonlinux show no icon in Slingshot, although in playonlinux and as desktop files in ~/.local/share/applications (as seen in the file manager) they have proper icons.
Looking in the desktop files (as text), the Icon line directs to image files in ~/.PlayOnLinux/icones/full_size. These image files are created there by Playonlinux when a desktop-file/shortcut is created: selecting Configure, selecting the virtual drive, then selecting to create a new shortcut for that. (To access the shortcuts in Slingshot the desktop files have to be copied from $HOME to ~/.local/share/applications, as mentioned in the question.)
The solution is:
- copy the image files to
~/.local/share/icons/ - rename them to include the
.pngextension (e.g. fromnametoname.png) - edit the
.desktopfile to have the lineIcon=name- replacingnameaccordingly.
