Rated 5 out of 5 stars

It is not fully disabled. In some places (I don't get the pattern) for enabled checkbox I see both empty squire (like it is disabled) _and_ enabled checkbox icon from your addon (i.e. both of them, but first one is inverted). Example is "Configuration Mania addon, "Browser", "Browser Cache", "Enable cache memory" option.

This review is for a previous version of the add-on (0.4.6). 

Thank you, it's fixed now.

Also if you prefer, you're welcome to email me issues instead of re-doing a review every time (me@choggi.org).

Rated 5 out of 5 stars

What Button Icons mode Disabled supposed to do? Under FF and TB I still see icons on each button in Disabled mode, f.e. right in about:addons

This review is for a previous version of the add-on (0.4.6). 

Yes, it should disable button icons. A fix I did for Linux button icons is overriding it, I'll have to do some testing to see what will work.

Edit: Working now

Rated 5 out of 5 stars

Customize still makes all mentioned icons empty as before and I notice that inactive Forward button is grey circle with white arrow instead of just grey arrow. Active Forward button is right.

This review is for a previous version of the add-on (0.4.6). 

Oops, sorry copied over the wrong file. Try it again.

Rated 5 out of 5 stars

When entering Customize Toolbar mode, lots of buttons lost their icons (empty), they are: Forward, Delete, Print, Mark, Stop, File, Archive, Next.
Their icons are properly restored after exiting Customize, but using them blindly while being in this mode is hard.

This review is for a previous version of the add-on (0.4.6). 

Right, I forgot about customize mode. Should be working fine now.

Rated 5 out of 5 stars

In the standard big toolbar all buttons are in the black/white style, but after addon installing Forward button becomes blue colored circle, which looks distracting.

This review is for a previous version of the add-on (0.4.6). 

Alright, all the toolbar buttons for TB should be fixed now.

Rated 4 out of 5 stars

After installing this addon on TB 45.0.1 (Win10) Delete big toolbar button icon becomes empty.

This review is for a previous version of the add-on (0.4.6). 

see if this fixes your issue
https://choggi.org/misc/CuteButtonsCrystalSVG/CuteButtonsCrystalSVG-0.4.7.xpi

if it does, you can make a copy of
Profile\extensions\CuteButtonsCrystalSVG@ChoGGi\content\Icons.css
go back to v0.4.6 and replace Profile\CuteButtonsSVG\Icons.css with the newer file.

Rated 5 out of 5 stars

FF 46.0.1 x64
Update: this bug is fixed in 0.4.7

This review is for a previous version of the add-on (0.4.6). 

Could you check to see if this also works for you as well, before I upload it.
https://choggi.org/misc/CuteButtonsCrystalSVG/CuteButtonsCrystalSVG-0.4.7.xpi