This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

I use taskbar in auto-hide mode and when firefox's window is maximized it hides the taskbar line making it impossible to use

more options

As the title says.

When I use firefox, the taskbar becomes hidden

I installed this instance on a fresh install of Win10 Education x64 and since then, I already did a clean install on firefox.

As you can see one of the pictures has that green line of taskbar on the bottom which the other picture clearly lacks.

Things I did/do not do:

- I'm not using firefox in fullscreen mode; only the window is maximized.
- I did not modify any graphical properties in the config tab.
- Did not modify the Taskbar Settings other then the "auto-hide" option (no tweakers and registry wizardry)

Things I did:

- Ran a windows update
- As I said I already did a clean install
- Tried with non-maximized window and Firefox sometimes still was above the taskbar on the Z-pane

The funny thing is, when I used my notebook as my primary pc for the last ~3 years, this bug was always present, not once did I managed to solve this problem, now that I built a pc and using it as the primary computer I did a clean install on the notebook and the bug is no longer present. On the first try it works perfectly. Now the bug is present on my PC. (Pictures included)

As the title says. When I use firefox, the taskbar becomes hidden I installed this instance on a fresh install of Win10 Education x64 and since then, I already did a clean install on firefox. As you can see one of the pictures has that green line of taskbar on the bottom which the other picture clearly lacks. Things I did/do not do: - I'm not using firefox in fullscreen mode; only the window is maximized. - I did not modify any graphical properties in the config tab. - Did not modify the Taskbar Settings other then the "auto-hide" option (no tweakers and registry wizardry) Things I did: - Ran a windows update - As I said I already did a clean install - Tried with non-maximized window and Firefox sometimes still was above the taskbar on the Z-pane The funny thing is, when I used my notebook as my primary pc for the last ~3 years, this bug was always present, not once did I managed to solve this problem, now that I built a pc and using it as the primary computer I did a clean install on the notebook and the bug is no longer present. On the first try it works perfectly. Now the bug is present on my PC. (Pictures included)
Attached screenshots

All Replies (3)

more options

Does your PC use multiple displays with different resolutions? That is one of the reasons Firefox might miscalculate the height of a maximized window.

Another issue is sometimes the settings file that stores window dimensions becomes corrupted with nonsensical values. You can rename the file and have Firefox rebuild it. Here's how:

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

  • "3-bar" menu button > "?" Help > 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, on the Profile Folder row, click the "Open Folder" button. This should launch a new window listing various files and folders in File Explorer.

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

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

Pause while Firefox finishes its cleanup, then rename xulstore.json to something like xulstoreOLD.json.

Start Firefox back up again. Do windows display normally again?

That mini-reset will hide the menu bar and bookmarks toolbar. 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 right-click the "+" button)
  • (menu bar) View > Toolbars
    On Windows, tap the Alt key to activate the menu bar temporarily.
  • in Customize mode > Toolbars button (see: Customize Firefox controls, buttons and toolbars)

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

Any improvement?

more options

I currently have 1 FHD display. Unfortunately regenerating the xulstore.json did not solve the problem

more options

Hi TToth, if the problem continues, could you use the link/button to the right or below my earlier reply to deselect it as the solution? Thanks.