1. print

File menu, print sheet, or {f p} invokes a print dialog that is very 
similar to pcb-rnd's. It does a ps export and passes it to lpr (or 
whatever command you specify).

For now it prints a single sheet. Later on there could be an option to 
print a whole project, with each sheet on a separate page (or file). I 
don't plan to have a multi-page/multi-file option on per layer basis, like 
we have in pcb-rnd, because in sch context separate printing layers 
doesn't seem to make any sense.

2. symbol meta layer

I've introduced a new display layer, called symbol meta. It's off by 
default. Similar to pcb-rnd, it draws the bbox of symbols (color 
configurable). Plus it prints an E or L mark, depending on whether the 
symbol is embedded or is coming from the local lib (more on this in a 
subsequent test request). 


3. attribute history traceback (GUI)

Open examples/slot2.lht, click on compile, then browse the abstract model 
(window menu/abstract model, or {w a}), navigate to U1. You'll see there's 
a portmap attribute. What if you want to change the pinout? You need to 
edit the portmap. That can not be done in the abstract model, only in the 
concrete model, in a symbol.

As a slotted component, there are 5 symbols contributing to it, and only 
one should have the portmap attribute. Normally you would need to go back 
to the sheet and find which symbol that is.

I've added a feature to make this easier: in the above abstract model 
window if you click the portmap attribute, its compilation history is 
printed in the lower right table is displayed. That's how you know where 
exactly the value is coming from, which is the "portmap" attribute 
of object /2/2. If you click on the "history src" button, sch-rnd will 
look this up for you and open the attribute editor of that object, cursor 
set to the source attribute so everything is ready for your modification.

If there are multiple sources in the bottom right list, sch-rnd 
auto-selects the one that determined the final value; you can also visit 
the other by selecting them, the "history src" button always takes you to 
the source that is selected. But most of the time there will be only one 
source.

(If the source of an attribute is another attribute in the abstract model, 
the abstract model window is kept and is changed to show the source 
attribute. After pressing the "history src" button a few times that's how 
you can travel back through a chain of abstract->abstract compilation 
steps to the final concrete source where you can make your edit.)