A Dynamic Device And History Window
The tool window should be dynamic like in the way propellerheads shop has a way to display in a grid view but changes to display them correctly without overlap or being half way outside the box. In addition to this the icons would scale either through preset sizes or manually in the resizable window.
The dynamic device window could be additionally accessed with an icon in the transport bar and display the last device added to the rack. When building complex setups knowing what you last did visually can help, this could be extended with a history of operations view and allow you to go back to a specific point in the creation of your track.