A major change to how symbols are handled has been merged into the development branch of KiCad. If you run nightly builds, this change will affect you in the very near future. Everyone who uses KiCad is familiar with adding aliases to symbols. This concept is now gone and has been replaced by symbol inheritance. This means that the “Aliases” panel in the symbol editor “Library Symbol Properties” dialog is now gone.
To create a symbol derived from another symbol (alias), create a new symbol and select the
root symbol from the list of root symbols that you wish to inherit from. If no symbol is selected in the “New Symbol” dialog, the symbol will be root symbol.
These changes required changes to the symbol editor behavior. Derived symbols cannot be edited except for a limited set of properties (the same properties that could be modified for aliases) using the “Library Symbol Properties” dialog.
The symbol editor window will show inherited symbol elements grayed out as shown below and all of the editing buttons will be disabled.
You now have to select the root sheet in order to change the root symbol elements. This also makes it clear when you are viewing a derived symbol versus a root symbol. Prior to this change, selecting an alias always allowed editing of the root symbol.
I know this is a major change and will require some adjustment but this is where the new symbol architecture is going. I don’t think it will take long to adjust to as it seems fairly intuitive if you understand the concept. This was a significant change so there are likely bugs. If you find any issues, please file a bug report so I can get them fixed.