GUI is broken in Ardour

[fuxoft]

In the latest Ardour (4.4) on Ubuntu Linux, the Protoplug window keeps flashing with about 1Hz frequency, which is very jarring. Also, the window cannot be easily resized because after first resizing, the "native" Protoplug resizer in the bottom right corner is hidden by encompassing Ardour frame. And resizing the Ardour frame does not resize the Protoplug window (it reverts back to original size after a fraction of second). Here is the video that shows how it looks: https://goo.gl/photos/eH4kZfFv7P2vesqN9