[Linux] Window is missing any decorations

[feliwir]

It's not possible to close MediaEditor, since the window is missing any close buttons in the window bar:

[DickyQi]

we using full screen window for application. and at left side menu toolbar. Last button is quit button, you can click it to exit app.

[WyvernZhao]

There are two ways to quit MEC under ubuntu:

1. By clicking the "quit" button on the left tool bar.
2. By clicking the "mec" task bar icon then click the "quit" menu item.

[feliwir]

we using full screen window for application. and at left side menu toolbar. Last button is quit button, you can click it to exit app.

The window is not fullscreen. I think people are used to having a "X" in the top-right corner.