Cool new tooltips in Firefox Nightly! Currently disabled by default while we do behavioural / accessibility review and ensure that it’s a total improvement over existing tooltips
browser.tabs.cardPreview.enabled to true (no restart required), you should get the cool tooltips!
Bug 1749345 - White screen for up to 30 sec after updating Firefox using the full installer, due to FirstStartup component
Codetribute:
Find a good first bug to start contributing on a Mozilla projects (Firefox, Thunderbird, and more). See the above link for creating a Bugzilla account first!