on archlinux/kde, the 'icon.source' in ToolButton can't work, just give blank. (but on windows work).

so I changed to use 'icon.name' with my own icon theme. for 'success', it work.
But for 'error', it always use system's icon.

I checked Button, it can work as expected.

I add two icon theme, 'debugger' and 'invert',
set icontheme to 'invert',
with 'icon.name' as 'success' both for ToolButton and Button,

It looks like the 'ToolButton' use 'debugger's icon, but Button use 'invert's icon.

i.e. same 'icon.name' result in different icon for ToolButton and Button.