minimum size for graphical object

Occasionally, my students, when drawing a mechanism with graphical boxes and reaction/resonance arrows, will insert in their drawing a box or arrow that is invisible.  I think they do it by clicking accidentally on the drawing pane instead of click-hold-dragging.  ACE sees the box or arrow and, being unable to interpret it as belonging to the mechanism, will often display an error message to the student.  But the student can't see the box or arrow to which ACE is objecting.  The only way to remove the offending object is to erase all visible objects, go to the source, find the XML for the remaining object, delete it, import, and redraw the desired objects.

This problem could be solved if Marvin set a minimum size for its graphical objects.  It wouldn't really matter what size it was, as long as it was visible to the naked eye.  

Hi Bob,

 

Thanks for this report; we will implement this feature in the graphical object drawing soon.

 

Best regards,

 

Akos

The attached file illustrates the problem.  Note that textboxes 9 and 14 both have MPoints with x and y coordinates of NaN.  I have no idea how the students generate such textboxes, but you should make it impossible for them to do.  The boxes are invisible and can only be found if you know enough to look at the XML.

Hi Bob,

Thanks for the file. We were not able to create invisible TextBoxes with NaN coordinates, but we've found some other issues when we tried to resize TextBoxes that might be related. We continue researching this bug, but if your students coud give hints what to do to create such TextBoxes it would be appreciated.

Best regards,

Peter

Here's what the student who drew the textbox said:

Well, I do remember that  when I would try to draw a textbox, it would occasionally disappear, leaving only a small vertical line in the lower portion of where the textbox was originally, but it would ultimately disappear and I would have to draw a new textbox for that step.  I have yet to recreate the problem though.  

Hi Bob,

Thanks for the information. We are investigating the issue and we will respond soon.

Best regards,

Peter

Here's another communication from the student.

I've managed to recreate the problem in the source, just not the feedback from ACE.  Problem 2 of the last assignment due Monday, when I entered a 3 in the textbox, it gave the small vertical line.  When I used the select feature to make the box bigger so the 3 would show, the box disappeared and I noticed the NaN values in the source.  

Thanks for further info.

Hi Bob,

We made some changes in textbox drawing to avoid the creation of small textboxes accidentally. The fix will be available in the next release (5.3.2).

Thanks for the help.

Best regards,

Peter