Make all features toggleable

[TanvirOnGH]

Description

Enhance the user chrome (*css) configuration by making all features toggleable using the @supports -moz-bool-pref directive. This will allow users to easily enable or disable specific customizations without modifying the CSS directly.

Example Implementation

Here's an example of how a feature can be made toggleable:

For Older versions (@supports -moz-bool-pref("PREFERENCE_NAME")):

@supports -moz-bool-pref("userchrome.horizontal-tab-bar-hidden.enabled") {
  #TabsToolbar {
    display: none !important;
  }
}

For Firefox 120+ (@media (-moz-bool-pref: "PREFERENCE_NAME")):

@media (-moz-bool-pref: "userchrome.horizontal-tab-bar-hidden.enabled") {
  #TabsToolbar {
    display: none !important;
  }
}

(not -moz-bool-pref("userchrome.horizontal-tab-bar-hidden.enabled")) is valid as well.

Benefits

• Reduces/Removes the need for users to edit the CSS file directly.
• Makes the configuration more modular and maintainable.

References

• https://udn.realityripple.com/docs/Mozilla/Gecko/Chrome/CSS/-moz-bool-pref