I've looked at this. From here, it seems you don't have the testing repo enabled. Edit slapt-getrc again. Change this
That tags the testing repo as "available but turned off" for GSlapt. I don't think slapt-get itself does anything with the #DISABLED tag.
Now start GSlapt. From the menu, Edit > Preferences, then the Sources tab (you might need to make this window wider). Check the box next to the testing repo. It's best that "untested" is off -- that sqlite build has been moved to testing. Click OK. When the suggestion appears to update package lists, click "Yes". That does the same thing as clicking "Update" in GSlapt's toolbar: Update the list of packages, not
you're ready to go look for more recent packages. But maybe not Firefox. It's possible I may be the only one having this problem, but take a look at this thread
. Some reply to that should come before too long.
You said in your reply to hata_ph that "I tried adding the above [repository] to slapt-getrc . . .". I take it that you added either the 32-bit or 64-bit line as appropriate, but not both. If you add a URL as "SOURCE=(urll_here)" or "#DISABLED=(url_here)", you'll be able to turn it off/on through GSlapt, otherwise probably not.
You should definitely turn untested off and enable it only long enough to grab exactly what you're looking for there. As for testing, the official wisdom is to leave it normally off, but this late in 7.0's cycle I find myself just leaving it on.