You need to edit the URL via the right-click context menu in the Properties of a bookmark. You can do this on the Bookmarks Toolbar and in the sidebar and in the Bookmarks Manager (Library).

If Firefox in unresponsive after you have clicked the star then there might be a problem with the places.sqlite database or with an extension.

• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

If you use Sync then best is to disconnect Sync temporarily during troubleshooting.

You can check for problems with the places.sqlite database (bookmarks and history) in the Firefox profile folder.

• use "Verify Integrity" button on the "Help -> Troubleshooting Information" (about:support) page
  in case errors are reported close and restart Firefox and retry

See also:

• http://kb.mozillazine.org/Locked_or_damaged_places.sqlite
• https://support.mozilla.org/en-US/kb/Bookmarks+not+saved#w_fix-the-bookmarks-file

If "Verify Integrity" button on the "Help -> Troubleshooting Information" (about:support) page cannot repair places.sqlite then remove all places.sqlite files in the Firefox profile folder. Firefox will rebuild places.sqlite and restore the bookmarks from a recent JSON backup in the bookmarkbackups folder.

• keep a backup copy of places.sqlite in case a new places.sqlite database has to be created
• http://kb.mozillazine.org/Unable_to_process_the_backup_file_-_Firefox

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

Thank you, I know how to edit bookmarks. This doesn't change the fact that the bookmarking dialogue is bad though.

And there are no extensions interfering with the places database. First, I don't have many installed. Second, it happened before installing most of them (with only uBlock Origin installed). Third, it also happens in private windows where extensions are disabled. Fourth, I even tried it in a fresh profile without anything changed from the defaults and the delay is still there.

I'm pretty sure the delay is some GUI "feature" that shouldn't be there.

It is possible to use code in userChrome.css to have the location field and the keyword visible all the time althouh you will have to be aware that these fields are also visible when they do not apply (e.g. a folder).

You can add code to the userChrome.css file below the default @namespace line.

• http://kb.mozillazine.org/userChrome.css
• https://www.userchrome.org/how-create-userchrome-css.html
• https://www.userchrome.org/what-is-userchrome-css.html

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* only needed once */

/* Bookmark This Page edit panel */
#editBMPanel_locationRow, #editBMPanel_keywordRow {
 visibility:visible!important;
}

/* Hide Giant Thumbnail and Favicon */
*|div#editBookmarkPanelFaviconContainer,
#editBookmarkPanelFaviconContainer,
#editBookmarkPanelImage {
 display: none !important;
}

You need to create the chrome folder (lowercase) in the <xxxxxxxx>.default profile folder if this folder doesn't exist.

• use a plain text editor to create a (new) <buserChrome.css</b> file in the <i>chrome folder (file name is case sensitive)
• paste the code in the userChrome.css file in the editor window
• make sure the userChrome.css file starts with the default @namespace line

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox