I am trying to understand under which conditions submenus disappear.

Now I have seen that the context panel is empty when submenues disappear.

Has anybody noticed the same and are there other instances when the context panel is emtpy?

Both effects could have the same rootcause.

Here is an example:
A -> no submenu

B -> Empty context panel

C -> Menu appears inside workspace (first time I see that)

Update

C seems to happen when the Maple window is not maximized to the full screen. -> then the context pannel becomes empty (for some reason) -> then if the Maple window is maximized to full screen we see C. Opeing new documents do not show this when toggling between and

In this post about a vibrating T-shaped structure, the ends of the T are traced over time.
The trace of the end encircled below in yellow fades with time

How to do the same with Maple? For example, can an attractor be animated this way?

My (intutive) interpretation of combine was so far in line with the combine help page

The combine function applies transformations which combine terms in sums,...

For the expression below I have to do the opposite (i.e. expand)

1/2 + cos(2*x)/2
                         1   1         
                         - + - cos(2 x)
                         2   2         

expand(%,trig)
                                  2
                            cos(x) 

Why is this and why does the context pannel offer (the ineffective) combine,trig on the first expression but not (the effective) expand,trig?

This cannot be a bug (this trig identity is so elementary) but I cannot make sense of it.

It happens from time to time that context menus do not appear. Normally, they appear at mouse-over (i.e. when the cursor is moved over an menu item).

Example: Right-click on input line

A Maple restart is required to get the normal behaviour back.

Recently I noticed that repeatedly clicking at different location on the menu item make the contex menus appear again.

This can be workarround if a restart is not acceptable.

It seems that the new Java IDE, which was introduced with Maple 2021, is more susceptible to this phenomen. 

All on Windows 10.

Since this behaviour is rare I could not identify a clear pattern which system state or event could be responsible for the appearance of this phenomen.

I would be interested if someone else has observed it and found another solution how to get the menus back without restarting Maple.

I was wondering if this has ever been discussed?

File preview would make life easier when searching an older document.

Since it seems to be a non trivial programming task, I was wondering whether generating a pdf document in parallel to a worksheet could be an option (in a subfolder). However, doing this by hand for all existing documents is not pratical.
 

Could this (generating pdf files) be done by a batchjob?