Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac=Options) key, and then starting Firefox. A small dialog should appear. Click Start In Safe Mode (not Refresh).

Is the problem still there

FredMcD said

Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac=Options) key, and then starting Firefox. A small dialog should appear. Click Start In Safe Mode (not Refresh). Is the problem still there

That solved it! Thank you, very much! :)

Safe Mode is a troubleshooting mode that temporarily turns off hardware acceleration, resets some settings, and disables add-ons (extensions and themes). If the problem goes away, that tells us one thing. If it does not, that tells us something else.

Type about:preferences#advanced<Enter> in the address bar. Under Advanced, Select General. Look for and turn off Use Hardware Acceleration.

Type about:addons<enter> in the address bar to open the Add-ons Manager. Hot key; <Control>(Mac=<Command>) <Shift> A)

On the left side of the page, select Appearance. Then select Default.

Now restart Firefox.

terlen64 said

I realize this may only be something cosmetic, but it is something that shouldn't happen. I've only noticed it in the past couple of days, since I upgraded to v47.0 (on a Slack64 v14.1 system). Everything, except that arrow, still seems to work as it always has. I'm not talking about the arrow on the "Downloads" button itself, but the animated arrow that shows a download has completed. It used to appear small, grow larger, and then disappear. Now, it does everything but disappear. Parts of it disappear if I hover over buttons it is covering. It disappears completely if I right click on the toolbar and select "Customize", or if I restart Firefox; I find both of those options to be a bit much.

Are you using the default Firefox theme or a full complete theme?

Are you using a GTK 3 theme?. Firefox as of 46.0 and newer needs GTK 3.4 (three.four) or preferably newer to run and as a result needs GTK 3 themes to theme Firefox. Firefox can look unthemed or potentially have gui glitches if a GTK 2 theme is in use.

Hi, Same problem for me. Seems to correspond more or less to the 47.0 version update. I have tried safe mode and this does indeed resolve the issue, so this is not a core problem. Hardware acceleration is off, and the selected (and only) theme is the default. I will say though, that it is not systematic... Sometimes a download will complete without causing the glitch. I haven't had any luck determining what exactly will set it off. It could be dependent on plug-ins, as safemode stops it (I have Adblock plus, HTTPSeverywhere, Distill and a few others for instance).

It could be the work of one of your add-ons. Type about:addons<enter> in the address bar to open your Add-ons Manager. Hot key; <Control>(Mac=<Command>)<Shift> A)

In the Add-ons Manager, on the left, select Extensions. Disable a few add-ons, then Restart Firefox.

Some added toolbar and anti-virus add-ons are known to cause Firefox issues. Disable All of them.

If the problem continues, disable some more (restarting FF). Continue until the problem is gone. After, you know what group is causing the issue. Re-enable the last group ONE AT A TIME (restarting FF) until the problem returns.

Once you think you found the problem, disable that and re-enable all the others, then restart again. Let us know who the suspect is, detective.

I think I have the culprit: Distill. It is a monitoring addon to keep track of changes in webpages. I ran a few tests with it on and off, and it would seem that it is indeed causing the bug. Not sure if you have the same one terlen64? Maybe if you don't you could go through the same procedure as me, testing with a few addons on and off to find which one is causing this in your browser? Or you could list which addons you have running – if you don't mind doing so — and someone might see a link between Distill and one of yours.

Marcool said

I think I have the culprit: Distill. It is a monitoring addon to keep track of changes in webpages. I ran a few tests with it on and off, and it would seem that it is indeed causing the bug. Not sure if you have the same one terlen64? Maybe if you don't you could go through the same procedure as me, testing with a few addons on and off to find which one is causing this in your browser? Or you could list which addons you have running – if you don't mind doing so — and someone might see a link between Distill and one of yours.

Never even heard of Distill until now. I run AdBlock Plus, NoScript, and SaveFrom.net Helper. I will do some testing.

And... nope. Just happened again. It is not Distill, but that means I have no idea what in the world is causing this bug to happen sometimes, and not others. It could even be that it is not addon related, and that if we ran safe-mode long enough and downloaded enough times it would happen then also. :/