When I create a custom toolbar in the main window (not the Editor window), there are command choices in the (Unassigned Items) group for Open new Diagram, Open new Browser, Open new Query Builder, Open new Editor, and Open new Automation as shown here:
After I add these to my custom toolbar, they work fine... unless I right-click on any Editor tab. Then they disappear from the toolbar, and they also disappear from the command list in the (Unassigned Items) group. I have to relaunch Toad to get them back.
Before right-clicking on Editor tab:
After right-clicking on Editor tab:
I am using TDP version 18.104.22.16894.