So if I have selected transparent as the color on a previous operation, and transparent sticks (as it in is still set to transparent when I go to use the operation again) If I want to change the color, I have to select the the eye dropper, select a random color then I can change the RGB values.
If I go straight to changing the RGB values, the swatch is recorded in the "previously used" but it is transparent unless you roll over it with the mouse and it is transparent if you try to use it.
The bug is minor, almost so minor it's not worth mentioning but I figured the program is so good, why let this little thing tarnish it.
(2019-10-25-14-40-54-066.png is without mouse hover)
(2019-10-25-14-41-23-344 is with mouse hover)