I want to post an update on the layout work. In
An Outline To Demonstrate The Script-based Layout System I provided a Leo outline that contained all the scripts needed for demonstrating how they can change Leo's pane arrangements ("layouts"). Since then I have been able to simplify the scripts, removed a few pesky bugs, added a new layout, and made sure the scripts run on Linux systems (which they mostly did before).
The new layout is the "Quadrant" layout originally devised by Jacob. It is a good test of the system because it inserts an additional splitter into the layout. The code for restoring the layout to the original default one is able to handle this added splitter without trouble.
For anyone who is following the technical aspects, I moved the permanent widget cache from the main splitter to c.frame.top. We want the location to be a permanently available widget derived from a QWidget, and this move gets the cache out of the very widget that is getting modified (so I could remove some special cases). I revised the restore code to take advantage of certain methods that QSplitters have that generic QWidgets do not. This allowed me to simplify the code and remove some bugs. It also speeded up the restore script. I was also able to simplify the initialization script.
Finally, there had been a problem with layouts that used the viewrendered plugin. About a month ago a breaking change was made to its interface that changed how it is instantiated. I added code that falls back to the old way so that people who haven't updated Leo for more than a month can still use these layouts.
Because of this change, trying to get help for Leo commands using F11 - or using the equivalent minibuffer command - may seem not to work. They do work but you will have to make VR/VR3 visible first. I don't plan to try to fix this because it would involve recent code in Leo's core that makes assumptions about what display elements will be available. I don't want to make any changes there until we have pretty well settled what the layout system will be like.
To try out the new version of the outline, unzip it, open it in Leo, and play with the "Layout Demo" menu that it adds to the menu bar (only for that outline - you can copy the commands and the menu over to myLeoSettings.leo if you want them to be available for all outlines).