internal-face-x-get-resource

internal-face-x-get-resource is a built-in function in `C source code'.

(internal-face-x-get-resource RESOURCE CLASS &optional FRAME)

Get the value of X resource RESOURCE, class CLASS.
Returned value is for the display of frame FRAME. If FRAME is not
specified or nil, use selected frame. This function exists because
ordinary `x-get-resource' doesn't take a frame argument.