> 2. Type "#0026FF" into the "Color name" field, then press Enter.
> 3. Click the "eyedropper" button.
> 4. Point at the current colour display field inside the dialog, then
> click (so as to select the colour.)
>
> Expected result:
> Nothing changes - as I've just selected what was already the current colour.
>
> Actual result:
> The colour does change. The "name" value changes to "#0024FF",
Your display is in 16-bit mode.
It uses only 16 bits for each pixel
(typically five bits for red, six for green, and five for blue, if I
recall correctly). A colour value like #0026FF uses eight bits for
each of red, green and blue. Thus the least significant bits of each
channel get truncated when it is actually displayed.