I tried to check the sample demo program "Actions_Vect" - it contains rulers and angles.
Firstly I put some objects on a ImageEnVect like rectangle, ellipse and then additinally I put 2 rulers and 2 angles. In the next step I wanted to merge all of them with background using option "Merge all to Background" and I lost some details for rulers and angle - see below.
In case of other objects (that means rectangle and ellipse) everything was all right (all were shown perfectly after merging with the background).
The same situation happens (I lost some details for rulers and angles), when I used option "print" or "export to pdf, jpg".
The next my discovery concerns position of this elements - the biggest problems are with ruler and angle that are positioned horizontally and vertically.
Why only rulers and angles lost some details and all other objects not? Maybe I made something wrong using ruler and angle?