pagelm

minor annoyance here. I have the background color button on my toolbar in Calc (Excel-equivalent).  Regardless of if I click on the icon on the arrow (for the dropdown) or directly on the button which shows my most recently used background color, it brings up the dropdown color menu with no selection for "last used" (other than hunting for it again in the list).  It becomes an issue for "did I use gray 30% there or gray 20%" and other subtle color changes.  It shows me on the icon what the last color used was, but it doesn't autohighlight it in the menu or anything.

Tried left click, right click, mid click, left cl+alt, left cl+control, left cl+shift.

 
If you right-click on the cell itself and choose the option of 'Format Cells..' there is a tab called 'background' of which it will show you what you used on that cell itself.
 
For example, a cell with a percentage of grey:
 

 
And another cell with a different percentage:
 

 
Minor annoyance as you just can't float to see those particular items and the menu itself won't hold at listing of the more frequently used shades but that is currently the only way I can determine if a cell is one background color or another. Might be something to suggest to the ones updating the features of LibreOffice so that a history of cell background colors can be buffered. 
 

pagelm
Any ideas as to how to click (or keyboard shortcut) a repeat of the last-used background/highlight color?  Without going into the full format cells menu or re-clicking on the color?

Not that I am aware of other than using the ctrl-1 function to bring up the cell properties and having to navigate to the background tab.

I suppose something with the format painter could be employed?  I can't remember if I used that in libre or if that was in the ms world, but it was in word/writer where I saw it, not excel/calc.  I'll hunt around for that myself, but if you have any more direct ways, let me know.  I'm willing to create a button with a macro as well if it comes to that (as long as I can have the button appear as part of my default interface)

 
The format painter is just an overall generic painting tool to copy a select range of cells and relate that formatting to other cells. It should copy all the formatting information for the transfer. It most likely will copy more than just background cell coloring.
 
According to some threads that I have found around on the libreoffice bug and help forums this particular thing should have been fixed in 3.4 and 3.5 respectively. It may have been broken in 3.6 and is no longer working. According to this thread answer it was fixed back in Feb 15th, 2012. Additionally it was noted as early as January 19th, 2012 that the functionality was fixed in Writer and carried over to Calc by Winfried Donkers. The issue at hand currently is that the background formatting for cells does not have the ability to historically remember the last used color setting. The workaround 'currently' being given is to create multiple style elements in calc and call those to be reused when needing to format different cell ranges or do a copy/paste special in order to get what you are looking to have done according to this thread.