
By far the most effective way of grouping and ungrouping objects is to set up a User Defined Button in the toolbox.
These are normally found in the resource area on the right of the toolbox, and look something like this:

These icons are customizable tools, meaning they can be assigned to perform a wide range of different functions… including grouping and ungrouping multiple objects
If for some reason these icons are not present in the main toolbox, they can be added from the Tool Store at any time.
Start by right clicking on one of the icons. A new window will appear titled Keystroke Definer, allowing you to change what the icon does.
Select Special Keystrokes from the three options on the left, then place a tick in the box marked Ctrl and select the letter G from the drop down list. If you want, you can also type the word ‘Group’ in the text box marked Tool Tip (this is the text which will be displayed whenever the mouse hovers over the icon).
Your window should now match the one shown in the screenshot below. Once it does, click OK to close the window.

From now on, clicking this icon will be the same as pressing Ctrl and G on the keyboard. If you want another button for ungrouping objects, simply repeat the process for the other icon and select Ctrl and U in the Keystroke Definer.
Try selecting a few objects and click the icon to see what happens!