To Locate and Select a Tool in a Child Toolbox (Without Floating the Child Toolbox)
In the parent toolbox, click the tool that is the representative of the child. While holding down the mouse button, move the pointer outside the button to open a pop-up menu immediately, or leave the pointer stationary for a delayed menu open.
The pop-up menu contains an item for each of the tools in the child toolbox.
Select the menu item that corresponds to the desired tool.
The selected tool will be displayed in the parent toolbox as the new representative of the child toolbox.