Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac=Options) key, and then starting Firefox. A small dialog should appear. Click Start In Safe Mode (not Refresh).

Is the problem still there?

Hello,

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Thank you!

Here are the screenshots. All the three buttons (i.e. Minimize, Maximize and Close) are hidden.

Moreover there are some weird lines on the task bar at the top. but when I bring the cursor to the top those lines go away. I have attached screenshots. Also, starting in safe didn't help solve the first problem.

Hello,

Try disabling graphics hardware acceleration. Since this feature was added to Firefox, it has gradually improved, but there still are a few glitches.

You will need to restart Firefox for this to take effect so save all work first (e.g., mail you are composing, online documents you're editing, etc.).

Then perform these steps:

1. Click the menu button and select Options on Windows or Preferences on Mac or Linux.
2. Select the Advanced panel and then the General tab.
3. Uncheck Use hardware acceleration when available.
4. Restart Firefox and see if the problems persist.

Did this fix your problems? Please report back to us!

If the problem is resolved, you should check for updates for your graphics driver by following the steps mentioned in these Knowledge base articles:

• Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

• Upgrade your graphics drivers to use hardware acceleration and WebGL

If your question is resolved by this or another answer, please take a minute to let us know. Thank you!