Make the browser warn me before moving away from unsaved changes.

[joergewald]

When I make changes, the save button turns yellow. I may not notice that, or the button may not be visible right now. In that case, when I move away from the page, the changes can be lost.

In other applications, I get a warning from the browser in this case.

Make the browser warn me before moving away from unsaved changes.

[biuti]

This should be added in all affected pages with 43fb32e.
Please close if fixed.