Megabar

[Odin2]

Is it no longer possible to preclude the locbar from enlarging when I focus on it?

[Ashleyj]

I think you will find there are now the following entries that need to be set to false -

browser.urlbar.update2 = false
browser.urlbar.update2.disableOneOffsHorizontalKeyNavigation = false
browser.urlbar.update2.oneOffsRefresh = false
browser.urlbar.update2.restyleBrowsingHistoryAsSearch = false

and

browser.urlbar.update2.emptySearchBehavior = 0

I was having the same problem but setting the above and browser.urlbar.openViewOnFocus = false fixed the issue.

[jscher2000]

"No longer" compared to when -- Firefox 76?

https://www.userchrome.org/megabar-styling-firefox-address-bar.html#enlargement

[dickvl]

See also:
viewtopic.php?f=38&t=3071140

[Odin2]

Thanks, all. Jscher's link seems to have done the trick.