The DxDesigner toolbar icon functions can be found in the MGC InfoHub DxDesigner Reference Manual. To review these select the Help > Documentation in InfoHub from the drop-down menu in DxDesigner.
When the InfoHub opens, under the Schematic Capture section, double-click the DxDesigner Reference Manual document.
In the left margin on the Contents tab, select the DxDesigner Menus, the menus are broken down into the DxDesigner drop-down menu catigories (i.e., File Menu, Edit Menu, View Menu, etc.), select one of these to open the link for that menu, all the commands for that menu, and the associated toolbar icon, are shown and described.
For example, on the drop-down Add Menu in DxD, the first command is Add Block:
The DxD Reference Manual describes the command and displays the toolbar icon:
Unfortunately I haven't been able to locate the Expedition PCB toolbar icon mappings. When I do, I'll follow-up on this thread.
I hope this helps!
Mentor Graphics SDD