I had the same problem (I think likely due to):
using XP + old browser versions (of IE, and no other browser on computer, lol)
so, I think~guessing roughly, the new 'CefSharp' version you used for quest v560, isn't compatible with either XP and~or old IE~other browser versions, whereas, the older 'CefSharp' version that you used for quest v55X (550 and 551), is compatible.
but, I don't really understand 'CefSharp' and etc stuff... but I think this is generally in the right direction... I hope... of why the error is occuring for us who need to get updated computers+browsers, lol.
No reason for you to waste time on this, as personally it is us, we really need to update on our side. You shouldn't have to make compatibility for outdated legacy stuff... I mean.... why not make quest compatible with pre-XP (win 98 and etc)... my point. OS win XP+Vista needs to be retired~dead~killed off fully, seriously, its our problem, not yours. Quest needs to be win 7 compatible (as it is still very popular and will likely last 10+ years like XP has, lol), but not outdated XP+Vista compatible, that's just too old for you to waste time on.
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so, he~she for now, just needs to download and install the quest v551, and he~she should hopefully be fine.
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@Red:
the 'missing' Tabs are now 'toggled' in quest v550+551+560, as there were too many of them cluttering up the GUI~Editor:
http://docs.textadventures.co.uk/quest/ ... notes.html (this is a really invaluable link, btw, and make sure you click on the individual 'blog' links for more and extra details, too)
you got to go into the 'game' Object and~or the individual Objects, (whatever the tags are called) Tags, to find the toggle options to show the missing Tabs
Go here:
http://textadventures.co.uk/quest/desktopthen click on the 'previous versions' button, and select version '551' = 5.5.1
this quest version should work for you...