Support for customColors prop for ui.colors

[Kolterdyx]

In the Quasar docs references by the ui.colors docs, there is a link to an adjacent page for the Quasar Color Palette config docs, where it shows that a customColors prop exists. I haven't used Quasar personally myself, but I'd assume it allows you to define custom color classes and use them like the main colors (primary, secondary, accent, etc.).

My idea would be to extend the ui.colors functionality to support more arguments the following way:

from nicegui import ui

ui.colors(myyellow='#ff0')
ui.button('I am yellow!', color='myyellow')

ui.run()

This canbe done manually by adding the required CSS and adding the color name to the QUASAR_COLORS set in nicegui.elements.mixins.color_elements before using it, but I think this is diving too deep into implementation details and should be avoided, and is instead more suited for a new feature.

I think this would be a nice feature to support to allow extended theming, and after tinkering a bit with the source, it would be really easy to implement, so I submitted a PR #3708

[falkoschindler]

PR #3708 has just been released. 🚀