Having opened a file with a long file name would result in a huge context menu.

The number is a guesstimation based on the task maximum width in normal panels but admittedly quite random.

Uses new API in D4257

Unfortunately here it just blatantly cuts off the contents (also with Fusion theme) and the menu is still placed as though it was as wide without the restrictions :/ Can someone with newer Qt (than 5.7.0) try if this is still an issue there?