The proposed new icons from your earlier post (mainly black and white, some dark blue here and there, almost full absence of colours, far less details, lack of outlines, general flat look) are the total opposite of the colourful GUI of Grasshopper.
Also, note that Grasshopper has a bunch of primary icons (16 by default) with a hexagonal shape that are 90% black. That does not mean that the entire Rhino UI should follow the same style. The majority of the rest icons on the top main toolbar in Grasshopper are very colourful and mainly square, shaped like a medium gray button with a strong black outline, which is another element that can’t be implemented as an icon design language in Rhino where the majority of icons are non-square shapes.
The funny thing is that Grasshopper’s geometry creation and modification icons are designed to fit a medium gray background (RGB 160, 160, 164), hence they are made of thick black lines and strong outline with offset shadow, plus orange fill colour (typically RGB 255, 195, 0) instead of Rhino’s classic blue (typically RGB 147, 167, 252).
RGB 255, 195, 0:
RGB 147, 167, 252:
Here is the interesting part. I use a noticeably lighter gray (RGB 190, 190, 190) for the background of my toolbars, which some people in the past called “too dark”. Well, GH’s background is much darker, yet it’s considered the most appropriate and “readable” by the developers and many users. I call this a biased opinion, because the darker gray background in GH makes reading the text and most icons (especially those with no orange fill, such like the curves) really hard to read.
Default Grasshopper:
My proposal:
Note: The above image is edited in Paint NET, hence it’s not a perfect example due to the limitations of this program’s tools to properly replace the colours. There is some pixelation letf that’s not easy to remove with Paint NET. Also, the offset shadows of the GH icons must be lighter, but the limitations of the program will not let me make that in a feasible way. Lighter shadows will make my proposed image much better looking.
When I proposed the neutral gray RGB 190, 190, 190 to be a default background colour in Rhino several years ago, some developers said that it’s inappropriate due to its “darkness”. Yet, somehow the much darker background in Grasshopper (RGB 160, 160, 164) is considered “light enough” to be readable.
The latter really don’t work well with the black text in GH.
RGB 190, 190, 190:
RGB 160, 160, 164: