Q: Gruping Grid GXT 2 How can I put the total values of a group of the grid in the same line with the type of the group? 
Like:
[-] Fruits                     $4.00
Banana                         $2.00
Apple                          $2.00
So when I have the group collapsed, I have this
[+] Fruits  $4.00

A: Use Live Group Summary. Link: Sencha GXT 2 LiveGroupSummary Example 
If you want to show the summary row at top, it will be a difficult task as there is no direct way of doing it.
You have  GXT classes GroupingView and GroupViewSummary which extends GroupingView. You can see in the doRender method of GroupingView, the header text is being generated. You will have to override the method by following the steps of renderSummary method of GroupSummaryView. The header and summary, both are created in different classes, so it will be  a difficult task. Just follow the implementation of GroupViewSummary which extends GroupingView and change the renderSummary and doRender method according to your need. 
I will not suggest doing so, because it might break the functionality.
