BUG: Select the initial background color doesn't work

Hi @tranthanhhoa & @RJCAM,

The bug indeed only appears when specifically selecting a background color value of #000000.

Tracking it down, it is due to the background-color property's default value of 'none' being set as '' by the color input. It later gets converted to #000000 by the color picker, whereas its actual value is rgba(0, 0, 0, 0) (or transparent).

The updated value is compared to the color picker's stored value on change, & nothing is done if they are equal (hence only failing when setting it to #000000).

I think this should be fixed by setting the background-color property's default value to transparent. Which should also allow to remove the special handling of the none value in the ColorInput.

As always, I'd be happy to open a PR if this looks good to you :).

@tranthanhhoa I'm not able to reproduce this bug in the demo (same as you), it's working fine here, check this:

What did you do before?

background-color property's default value to transparent worked for me. Thank you so much @mcottret !