uploading screenshots to steam on Linux

My steam overlay is not working. I have no idea why.
I enabled it both from Steam->Settings->In-Game and for each game separately, I added
LD_PRELOAD='/home/USER/.local/share/Steam/ubuntu12_32/gameoverlayrenderer.so'
as a game option, I changed all possible key-bindings to something free. And still, nada.
I checked the output of: 
$cat /tmp/dumps/`id -un`_stdout.txt
nothing very informative but some ELF errors which too annoying to even start working on.
So for the moment I'm leaving it aside and posting the workaround.
What I did is this:
https://steamcommunity.com/sharedfiles/filedetails/?id=1358157391
If you do what's described using Chrome, it actually uploads your screenshots as a screenshot, not as art. So that's something I guess.
In brief:
 Load http://steamcommunity.com/sharedfiles/edititem/767/3/
Press
Ctrl + Shift + J
Then paste into the console
$J('#image_width').val('1000'); 
$J('#image_height').val('1'); 
$J('[name="file_type"]').val("5");
And press enter. It gives some kind of error but still, it works. So after choosing your file and describing it, you end up with a Screenshot! :)
The only problem is that you cannot add tags, so it won't go to the Community Hub.