System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 441.28

Blender Version
Broken: version: 2.82 (sub 7), branch: master, commit date: 2020-03-12 05:06, hash: rB375c7dc4caf4

Short description of error
Render window menu disappears/offset when launching a second rendering.

Exact steps for others to reproduce the error

• Launch the attached file in Blender. It can also be any file that you create in Blender. As far as I know, this problem has been present for years.
• Press F12 to launch the first rendering and open the render window at the same time.
• Press F12 again to launch a second rendering. Sometimes, the problem occurs on the third rendering.
• At this point, you should see the menu disappearing behind the window’s top bar.

I attached three screenshots demonstrating different characteristics of the problem.

RenderWindow-WindowMode.jpg

• It is still possible to move the cursor over the menu bar to activate the menu of other buttons, but the visible area is very thin.
• The menu bar appears to have an offset towards the top.

RenderWindow-Maximized1.jpg

• The maximized version does not have any menu visible or that appears to have any offset.

RenderWindow-Maximized2.jpg

• The maximized version on this one shows a “hand” button at the top-right corner. It shows a certain offset. When trying to click on the top of the window in the rendering area, it is still possible to activate certain elements. For example, in this screenshot, the button “Browse Image to be linked” has been clicked. This is why the drop-down menu is shown on this screenshot.

I also noted that the raw screenshots “RenderWindow-Maximized1.jpg” and “RenderWindow-Maximized2.jpg” do not have the same height, although both windows have been maximized. I ignore the reason at the moment.

Notes

When taking the screenshots, I used the Alt + Print Screen button on the keyboard to capture only the window (without the Windows task bar and other parts of the screen). Surprisingly, on the image “RenderWindow-WindowMode.jpg”, we can see the task bar. Normally, we would not see the task bar when capturing only the window with Alt + Print Screen. This information indicates that the rending window area was probably covering the task bar at the bottom, but with transparency. Capturing only the window’s content also captured what was behind the transparent area: the task bar in this case.

Another behavior that might explain the bug is about the fact that when pressing F12 to launch the second rendering, the window is automatically resized. Blender tries to maximize the covered area to nearly the maximum space that the window can occupy on the screen. A suggestion is to avoid resizing the window every time a rendering is launched. It might have something to do with the bug, but I also found this very annoying because this prevents ourselves from setting up our window layout as we would normally do with other windows.

After resizing the render window, if launching another rendering, the menu bar does not disappear. However, the window is resized. Launching another rendering just after (without resizing the window) makes the menu bar disappear.

I use a dual-monitor configuration in case that might influence.

Workaround

• One way to recover this problem is to use the “Maximize” and “Restore Down” button on the window’s top bar.
• Double-click the window’s top bar is one simple way to make the menu reappear just after launching the rendering.
• Clicking on the window’s top bar to move it makes the menu reappear.