Hi @ratfink and welcome aboard 
I appreciate your frustration. and Yep, when I leave Pinegrow for a while, its tools slip my memory and it frustrates me too, but first a few things for you.
- .dwt files… there are TWO types and they don’t play nicely together.
Dreamweaver uses that extension and Expression web use that file extension, but they are different.
each app doesn’t read a .dwt file correctly from the other app. even though they have the same extension!
I’ll let you figure that one out as it makes no sense to me.
The template styling the code you cant see appears to be in comments apparently ,you might find this threads explanations helpful from a year ago (you can use the search function in this forum to look for things)
Expression Web Pages, DWT Master Page - #3 by texxsmith
and from the year before that, someone else was having difficulty "importing* (using) the templated pages from Dreamweaver into Pinegrow.
@Terry44 above helped out on that one too
"Can't select element created at run time" error
That was due to malformed html , in case you come across that (and your code not showing up) as. you described.
Other wise. Yep I agree with you about the UNDO action. something is NOT RIGHT about it.
I haven’t explored it much in this new 5.2 version, but I haven’t noticed it listed as fixed.
What I find is that if I have SEVERAL PAGES OPEN in the text editor - which is quite normal.
and then click CTRL +Z - then … I have NO IDEA which of those pages are to be affected!
I would expect it to be JUST THE ONE THAT IS CURRENTLY BEING WORKED ON.
but this is not always so. quite often it is ALL OF THEM! or a different one and then I cannot CTRL+Shift+Z to redo.
and if I have saved it , then the HISTORY tab - the recycle, circular arrow tab - often NO LONGER shows the previous version. If I go BACK 4 version, hit save then ALL THE VERSIONS AFTER that are gone.
You, I and several others have mentioned this.
It Really needs looking at , or , better documentation to explain why it appears to be FUBAR in case some of us (including me!) don’t understand how to use it correctly or just what it is doing.
Once it has done its undo thing to all your work, that’s it. its gone 
Now! Using Pinegrow!
yep confusing, until you put the time in and become familiar. Yep it confuses me too when I forget how to do stuff after being away from it, which is often.
You say:
How many pages are you using? I guess you mean that you’re using a framework (bootstrap ,your own etc) as well as your now css stylesheet (or inline styles which You haven’t yet saved to an external stylesheet) and are looking for the
ACTUAL < CORRECT FINAL CSS STYLE RULE that … makes the change you want?
And the CORRECT style sheet it is in.
OR
THE ONE that you should OVERULE the FRAMEWork Stylesheet in/SAVE YOUR NEW RULE IN>
So that it…just works?
If so, yep, that can be totally confusing unless you have a good grip of the whole C …ss thing.
the C is the Cascade.
If you totally get this already, please forgive me as Im’m trying to work out all your queries to help>
I’m just another user and you say you have seen All the Documentation and ALL the videos.
Well done! I haven’t I see new things in them all the time and are constantly reminded of loads I have forgot!.
Right I was going to write something out for you here, but based on:
and
Well, actually with this part, you can! this bit DOES work really well )
But is only REALLY useful if you know exactly what you’re doing and If it shows you WHAT You were expecting.
If you have no idea or are confused by the whole Cascading of the css thing then, yep, this is mind blowing.
which leads to the. next bit.
If you are using FRAMEWORKS… which have hundreds of classes in a stylesheet,
(like 500 or something - this is why Pinegrow is SO useful - if. you can remember ANY of those, well done)
Then you will have the Bootstrap stylesheets.
you will also have your own,
you will have inline styles. until you save in an external style sheet.
You might have !important styles to mess everything up.
and if you have both frameworks AND your own and then open up Pinegrow, you have
styles tab and Properties tab.
Which to use? FIRST ? where is the ACTUAL one which makes the Difference?
Then the VISUAL Helpers?
WHICH ONE TO USE? They look the same!
why is there two for the SAME THING?
And the above is for EACH INDIVIDUAL
HTML ELEMENT or
FRAMEWORK COMPONENT
you click on.
if there are NO framework properties…then that entire section will be empty(hidden in your words maybe?)
if there are NO bespoke classes then Likewise.
ALSO… in the visual helpers HEADINGS below…if they are COLLAPSED but something is styled inside it, then… that should be BLUE to indicate for you to click it to expand and view the styling info.
…which will be listed above (er unless its. pseudo class…withing a media query…then you have to HUNT it down - bit of a faux pas on that one really.)
This could do with a little tweaking, if anyone wants to do a better version but better to wait until the OP gets back to us I think to clarify his queries.
if THIS description and the image above looks like the seed your confusion,
then please confirm and say just exactly how your trying to use it frameworks etc and then I and others will try to help.
IF, for instance you have clicked on element that has NO BOOTSTRAP component or styling then that top left box and underneath VISUAL STYLING TOOL… might be empty!±
The more information the better, even though it will drive you nuts to do so.
but tbh I will create some help things for you (or others beat me too it ) but I will also point you to the correct vids and tutorials, because it sounds like you may not have the best of grasps of just how Pinegrow works/to help you.
Which is understandable as it is BOTH a visual helper AND a code helper.
if you usually only do one. yes You will be stuffed/confused, until you come to appreciate that this does BOTH at the same time and so give you oodles of power too…shoot yourself in your own feet, if you don’t have adequate understanding of the whole cascade/ framework stylesheet /rule overriding thing
as well as style inheritance.
If you totally understand everything above, with regards basic stylesheet usage etc I might be at a loss.
so the more information the better.
for instance ,if your using COMPONENTS from FRAMEWORKS like say a NavBar (Viz. Bootstrap)
then it is created with and styled with BOOTSTRAP classes
FIRST
like it says from this point in this vid
Also, I have finally found THIS bit.
This is a good video by @matjaz (I find ALL his explanations to be superb and, frankly faultless! Perfect)
here, this will play at the exact point where he explains the SIMILARITY and difference between two very similar bits of the visual styling that are EASILY confused - it took me ages to break out of that that swamp…
here
this is a half hour video but THS POINT where the vid starts is very important with regards usage of both framework classes, your own classes and the pinegrow visual helpers and Interface.
and as you can see in the pic I posted earlier, now with moveable panels I have separated both of these so that I can now see them side by side. A BIG HELP!
If you are Using bootstrap for instance, another way to modify its variables and find your way around is explained in this excellent vid explaining how to create a Custom SCSS file, based on the original Bootstrap SCSS files (which then compile into CSS, just in case you’re not familiar with them - Pinegrow does this for you automatically)
here
If I am along the right lines and give more info then I will find and order the existing docs/vids in a way to explain to you and pad them out where it is lacking.
If you feel none of this is relevant, then I wont