Hi Mark, the size and position of the Save As dialog is stored by Firefox in a settings file that sometime accumulates nonsensical positions/dimensions. You can rename the file and have Firefox generate a new one with default settings to see whether that helps.

Open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" button > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, click the "Open Folder"/"Open Directory" button. This should launch a new window listing various files and folders in your default file viewer.

Leaving that window open, switch back to Firefox and Exit, either:

• "3-bar" menu button > "power" button
• (menu bar) File > Exit/Quit

Pause while Firefox finishes its cleanup, then rename xulstore.json to something like xulstore.old. If you see a file named localstore.rdf, rename that one to localstore.old.

Start Firefox back up again. Any improvement?

To turn the Bookmarks Toolbar back on,you can use one of these methods to show the toolbar list and select the desired bars there:

• right-click a blank spot on the tab bar (or the "+" button)
• tap the Alt key to activate the classic menu bar > View > Toolbars
• in Customize mode > Show/Hide Toolbars (see: Customize Firefox controls, buttons and toolbars)

To turn on the Bookmarks Toolbar, or other bars, click it on the list.

Thank you, that was interesting. "about:support" gave me a page with an "Open Directory" button but clicking that in safe mode just printed on the console,

• • (firefox:24628): WARNING **: Cannot launch default application: No application is registered as handling this file

Still, thanks to your hint, with Firefox closed I found and moved the xulstore.json file out to /tmp and indeed when I started Firefox again the main window appeared with the default geometry instead of how I had last had it.

Unfortunately, clicking "Save Page" still gives me a wholly blank white screen from which I can back up by hitting Escape.

Cheers, Mark

(I should add that I didn't have a localstore.rdf file.)

As a Windows user, I am not personally familiar with different Linux builds, but someone more knowledgeable than I posted this a while back:

There was a theme change with Firefox as of 46.0 as it requires GTk 3.4 or later to run so as a result you need GTK3 themes as GTK2 themes will not work.

Not sure whether that is related to the problem.

Maybe disable the native file picker and switch to the built-in Firefox file picker if the native version isn't working.

• ui.allow_platform_file_picker = false