You'll find those buttons in the top right corner - not the left.

You can make the title bar visible via the "Title Bar" button at the bottom left in the Customize palette window.

• Firefox menu button > Customize
• View > Toolbars > Customize

Sorry, yea. I mean the those buttons on the top right corner was gone when I maximised the FF's window.

Thx cor, I've tried, but those three buttons still invisible from the top right corner when the window was maximised

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Thanks Cor, the problem have now been solved. A plug-in causes this chaos.

as the image shown on Capture.png, the three button was there, when the window was on a Normal size. as the time when the screen was maximised, those three button was disappeared from their position (shown on capture1.png).

Im using the theme: FT DeepDark 10.3.8, which made by Steva on a 64 bit Windows 7 ult + sp1, with Intel Core Duo P8700 + 8G RAM, + ATI 4650 with Catalyst 14.4.

However, those button dose exists on my another computer which use a Intel I7 4770 + 8G RAM 6 + ATI R9 with Catalyst 14.4

I was having this problem, and what resolved it for me, I believe, was either unchecking "Run this program in compatibility mode for: Windows XP Service Pack 3", which is an option under Properties on the Compatibility tab, or it may have just been a matter of restarting the PC after the installation.