Hey man, I can't give screenshot evidence RIGHT now but I have tested 2 things in (iirc) "Ubuntu 12.04 LTS" 64-bit in the past, they worked perfectly although the game performance would lag when fullscreen (But I believe I had something wrong with my drivers). This was a few months back. I'll go check it out in a moment with an export of a project using the current version of Construct 2, and I'll post results. (I'm not a massive linux user, I have it dual-booted with Windows 7, which I use primarily, so gotta rebootz.)
EDIT: Goddamn I don't get Ubuntu. Took me a while to get it working but only because I had exported it into my external harddrive rather than the same harddrive that Ubuntu is installed in. SO I moved the files onto main harddrive and Linux64 ran perfectly, actually maintained 60fps more than when I ran the NodeWebkit export on windows! However, maximizing the game makes it lag like I mentioned before this edit.
So I hit Printscreen, it lets me pick where to save the screenshot. I pick my external harddrive, it gets angry and says I cannot, so I place it in a new folder in my main harddrive, and I take a few more screenshots.
I just rebooted back into windows and then I realise all but 1 screenshots are missing, and the one screenshot is broken. <img src="smileys/smiley5.gif" border="0" align="middle" />
So, since I didn't want to have done that for no reason, here's a screenshot of the broken screenshot. <img src="smileys/smiley36.gif" border="0" align="middle" />
[Removed, pointeless lol]
tl;dr, Construct 2 [R147]'s Node-Webkit export works perfect in Ubuntu 12.04 LTS 64-bit, aside from lag for me in fullscreen. 32-bit doesn't seem to run at all (But that's safely assumed that it's because the install of Ubuntu is 64-bit)