In the box that lets you select the background color of a cell, it would be nice if there was an eyedropper icon that you could click, that would select the existing background color of a cell (this could apply to font color too). I'm not colorblind, and even I have trouble differentiating between multiple shades of green to pick the exact same green I used before. I can see that it is wrong after I pick it, but then I have to pick it again. For someone who is actually colorblind trying to work on an existing file made by someone else and keep consistent colors. I thought maybe the eyedropper was just missing from the drop down because it isn't a modal, so the default behavior is to close when someone clicks outside it. But even the Custom Color screen doesn't have that option. So, I would add the change by: Adding an eyedropper icon to the background color dropdown. When clicked, it closes the dropdown and turns the users cursor into an eyedropper. After they click a cell, the selected background color becomes the background color of whatever cell they clicked and the cursor reverts to normal. And that's it. And maybe give the option to blind that to a shortcut key, so if you like hit CTRL+B, your cursor turns into an eyedropper, and the next cell you click, it will 'suck up' its background color.
Without relation to the eyedropper request, there is a way to copy the background color of a cell from the "format cell" dialog, where you can see the RGB/HEX values. There is also a way to copy the font color from the "font color > custom color" dialog. Of course there is the possibility of a simple copy format (clone) a cell, which includes those properties. Sure, an eyedropper feature might be simpler for users. I am just pointing out that there are alternatives available (as oppose to being some random try-and-error iteration attempts).
In effect we already have this, just not in the "eyedropper" motif--and see also bug 93813 to rework the SD color replacment. That is, the 'Background Color' TB button opens the common color picker displaying the active palette (usually 'Standard'). And across the bottom is a swatch bar with the 12 most 'Recent' colors across the UI (so not just current Calc session). What is not obvious, is that for any cell on the sheet selected, launching the 'Background Color' picker's button link to the 'Custom color...' dialog will show the bg color of the cell. Likewise for the 'Font Color' picker's link to 'Custom color...' where dialog will show the fg color for font in the cell. Between the two, it is trivial to match colors for those occasions when the 12 swatch recent bar is insufficient, a textual copy/paste of the RGB. Not quite dropper style, and could be enhanced to pass RGBA values back to the Recent swatch bar for bg fill or fg text.
With the existing two workarounds (Recent palette, and the copy-paste of colour code), I see this as a clear duplicate of bug 93813. See also bug 130967, which is already marked as duplicate It might be added to the widgets as part of a fix, and if not, it would be a follow-up enhancement request. Let's consolidate. Thank you! *** This bug has been marked as a duplicate of bug 93813 ***