I discovered the bug
Edited the rsgallery default template file...
components/com_rsgallery2/templates/tables/css/template.css
Then I removed this code
/* utility selector, this is common in many templates, but we can't count on it being there */
.clr{
clear: both;
line-height: 0px;
}
Now the default template is working fine with this rockettheme template.
I've made a new RS template, by cloning default and removing the "bad" css code, if anyone wants it, I'll upload it
See ya