Sometimes I want to quickly use a color that I see on a picture, website or program.
I usually take a screenshot then open it in Gimp and use the "Color Picker" tool.
Is there another way to do this in Gimp, without the screenshot step?
Or is it a bad idea to begin with?
I am on Linux, but I would appreciate a method that works on all platforms where GIMP is available.
You can use the color picker button in GIMP's color selection dialog or dockable (the one that opens e.g. when you change the foreground or background color).
It works like this:
You will encounter one issue, however:
On 32 bit Windows platforms, the only color you'll be able to pick this way is black - this is a problem in the Cairo library on those platforms, see bug reports https://bugzilla.gnome.org/show_bug.cgi?id=676708 for GIMP and https://bugs.freedesktop.org/show_bug.cgi?id=69617 for Cairo.