User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Firefox/68.0

Steps to reproduce:

Maximised the Firefox window after it having been minimised.

Actual results:

Parts of the displayed page are replaced with those from another tab.

Expected results:

The web page should be displayed correctly.

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It's probably not useful information but when I maximise the windows and the page is garbled, if I minimise and then maximise the window again it makes no difference. Only switching to another tab and back again causes the page to be rendered correctly.

How easily can you reproduce this?

Although I haven't figured out how to deliberately trigger the bug, it does happen on a fairly regular basis.

Simon, can you try disabling picture caching by setting gfx.webrender.picture-caching to false and see if the problem still happens?

Simon, did disabling picture caching help?

Disabling gfx.webrender.picture-caching does seem to prevent the bug.

Does it seem limited to particular pages / sites, or can it happen randomly on any page?

I haven't had any luck reproducing this yet on a Win10 + nVidia GTX 1050.

A few questions, in case I'm doing the repro steps incorrectly:

• What resolution are you running at?
• Could you clarify what you mean by minimize / maximize? I'm assuming that means minimizing to the task bar, and then restoring it by clicking on the icon on the task bar, is that right? And is the size of the window in this case the full screen size, or a window that only takes up part of the screen? Does the size of the window change in these steps, or just whether it's minimized to the task bar?
• Does it seem dependent on whether the window is minimized for a short or long time? Is there anything else you're doing on the PC between minimizing and maximizing?
• Jeff, has anyone in Toronto seen this / able to try and reproduce?

Thanks!

Does it seem limited to particular pages / sites, or can it happen randomly on any page?

I haven't noticed a pattern with any particular website(s).

What resolution are you running at?

1920 x 1080.

Could you clarify what you mean by minimize / maximize? I'm assuming that means minimizing to the task bar, and then restoring it by clicking on the icon on the task bar, is that right? And is the size of the window in this case the full screen size, or a window that only takes up part of the screen? Does the size of the window change in these steps, or just whether it's minimized to the task bar?

Yeah, minimising and restoring from the task bar. The window is maximised and doesn't change size.

Does it seem dependent on whether the window is minimized for a short or long time? Is there anything else you're doing on the PC between minimizing and maximizing?

It may be that the window needs to be minimised for a relatively long period of time. I'll experiment with this and give feedback.

Are you still seeing this?

I haven't experienced it in a while so it does look like it might be working now.