Are you able to move other windows around on the screen. Normally when the issue continues in safe mode, it is an issue with the install itself.

Certain Firefox problems can be solved by performing a Clean reinstall. This means you remove Firefox program files and then reinstall Firefox. Please follow these steps:

Note: You might want to print these steps or view them in another browser.

1. Download the latest Desktop version of Firefox from mozilla.org (or choose the download for your operating system and language from this page) and save the setup file to your computer.
2. After the download finishes, close all Firefox windows (or open the Firefox menu and click the close button ).
3. Delete the Firefox installation folder, which is located in one of these locations, by default:
   • Mac: Delete Firefox from the Applications folder.
4. Now, go ahead and reinstall Firefox:
   1. Double-click the downloaded installation file and go through the steps of the installation wizard.
   2. Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.

More information about reinstalling Firefox can be found here.

WARNING: Do not use a third party uninstaller as part of this process. Doing so could permanently delete your Firefox profile data, including but not limited to, extensions, cache, cookies, bookmarks, personal settings and saved passwords. These cannot be easily recovered unless they have been backed up to an external device! See Back up and restore information in Firefox profiles.

Please report back to say if this helped you!

HI,

I followed the instructions for a clean reinstall on my mac and even started it in safe mode. The problem, which is that I can not move Firefox around of the computer terminal persists. I contacted Apple and they speculated that since I am using a new iMac 5K retina, that this version of Firefox may have some problems running on this hardware. Obviously, I cannot confirm that, I can only report that on my machine, I cannot move Firefox (except to resize it). Any further information would be helpful. If Mozilla can test this and determine if it is a software bug (relative to the 5K retina iMac) that would be very helpful.

--Seth

sethansell said

I am running F.F. version 34.0.5 on a iMac with Retina display (32 GB RAM) and Mac OS X 10.10.1 I can resize the Mozilla window but I cannot move it around the screen. I have tried resetting Firefox and also turned off hardware acceleration. I've tried staring it in Safe Mode, and this does not help. All of my extensions are disabled and my plug ins are all set to "never active". None of these steps fixes this problem.

Please file a bug report on Bugzilla so our team of developers can look into it.

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

You might need to restart Firefox in order 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. Open Firefox Options window (Preferences on Mac or Linux) as follows:
   • In Firefox 29.0 and above, click the menu button and select Options for Windows or Preferences on Mac or Linux.
   • In Firefox 28.0 and previous versions, click the orange Firefox button at the top left, then select the "Options" button, or, if there is no Firefox button at the top, go to Tools > Options.
2. In the Firefox Options (or Preferences) window, click the Advanced tab, then select General.
3. In the settings list, you should find the Use hardware acceleration when available checkbox. Uncheck this checkbox.
4. Now, restart Firefox and see if the problems persist.

Additionally, please check for updates for your graphics driver by following the steps mentioned in the following 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

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

I unchecked the "Use hardware acceleration when available" and the problem still occurs both when Firefox is started in regular and in safe modes :-(

Has Firefox ever worked properly on this system?

Firefox has never worked properly on this system. I bought this computer yesterday. Apple tech support suggests that Firefox may not yet run probably on the iMac 5K Retina as it uses higher resolution than any other computer.

Any thoughts?

--Seth

If it has never worked properly, then Apple is most likely right. Please file a report on Bugzilla so our developers can investigate and repair the issue.

You may have a corrupt xulstore.json file. https://support.mozilla.org/en-US/kb/changes-toolbars-and-window-sizes-are-not-saved