When panel row size is set to 26, restart action icon is monochromatic. When I set row size to 36 all action icons are in color. I use xfce elementary darker mode.   Also, i found in Transmission play and pause icons are monochromatics, while remove icon is red... I don't know about you guys, but my opinion is that for consistency all these icons should be colorful...  One more thing, I think this icon looks outdated and needs a redesign. 