People have been confused by spotlight modals when they open on top of content pages as the window modal has a subtle background effect that overlays the whole browser window but can be especially hard to tell if the page and browser UI is already dark, so it's not clear that the message is coming from Firefox vs page. E.g., bug 1835158, comments in bug 1835175. The upgrade spotlight shown already has special behavior to open Firefox Home to show the message: https://searchfox.org/mozilla-central/rev/ae8629b27d8e0b187ebc1816be0c25bfd68bf955/browser/components/BrowserGlue.sys.mjs#4353,4364,4379,4383 Although that previously was a window modal and now a tab modal since bug 1789008 as there were multiple screens and avoided blocking the usage of the rest of the browser. Various visual aspects of the modal can already be configured like the backdrop from bug 1752936: https://searchfox.org/mozilla-central/rev/ae8629b27d8e0b187ebc1816be0c25bfd68bf955/browser/components/newtab/content-src/aboutwelcome/components/MultiStageAboutWelcome.jsx#202
Bug 1835481 Comment 0 Edit History
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People have been confused by spotlight modals when they open on top of content pages as the window modal has a subtle background effect that overlays the whole browser window but can be especially hard to tell if the page and browser UI is already dark, so it's not clear that the message is coming from Firefox vs page. E.g., bug 1835158, comments in bug 1835175. The upgrade spotlight already has special behavior to open Firefox Home to show the message: https://searchfox.org/mozilla-central/rev/ae8629b27d8e0b187ebc1816be0c25bfd68bf955/browser/components/BrowserGlue.sys.mjs#4353,4364,4379,4383 Although that previously was a window modal and now a tab modal since bug 1789008 as there were multiple screens and avoided blocking the usage of the rest of the browser. Various visual aspects of the modal can already be configured like the backdrop from bug 1752936: https://searchfox.org/mozilla-central/rev/ae8629b27d8e0b187ebc1816be0c25bfd68bf955/browser/components/newtab/content-src/aboutwelcome/components/MultiStageAboutWelcome.jsx#202