Lazarus 2.0.2 - WEBCore 18.104.22.168 :
Is this a Pas2JS compiler problem?
I believe this is related to how PNG graphics are persisted in the LFM file (versus the DFM file in Delphi). It looks as such to be an IDE plugin issue. We'll investigate to find a solution.
Its a big problem with most of the FNC UI controls like TMSFNCTreeView, TMSFNCPageControl, TMSFNCPlanner and others. They all have predefined pages and items with PNG images. Also a lot of properties stored in the .lfm files can not be found out of the box, I found some of them somewhere in WEBLib.TMSFNC files, but in general these complex controls are not running on a WebForm out of the box.
Should be fixed now.