I tried to build Seamly2D from source on my Ubuntu 18.04 and it failed. It turns out that commit bb3d1bdf93efbe1aa4120c2fb0b1460807983f6e made a small change:
- list.swap(k, s-(1+k)); + list.swapItemsAt(k, s-(1+k));
swapItemsAt is a new function only added since Qt5.13 (released 2019-06-19). My Ubuntu only has 5.9. If I revert the above one-line change it all builds fine.
So either the above should be changed back or the build requirements bumped.