I've added some comments in the code ; thank you Fabian.

Done. Thanks for this comment Eduard !

Thanks Evgeny ; that's a more elegant approach !

Thank you Daniel.

Actually I've found another way to do it without modifying any % classes !

1. using Studio, create a class which inherits from "%DeepSee.UI.MDXExcel" ; ie : "MDX.export.cls"

2. overwrite in MDX.export.cls what you need to modify to fit your expected rendering in the appropriate methods : 

OnPage, %PrintListingResult, or %PrintResults ...

3. in your DeepSee dashboard,  

replace the  Export Excel parameter of your widget, corresponding to this line in our .dashboard.DFI definition : 

<property name="excel">1</property>

by a new navigate control which calls your MDX.export class :

<control name="" action="navigate" target="*" targetProperty="./MDX.export.zen?MDX=...mdx query..." location="widget" type="auto" controlClass="" label="Export Excel" title="" value="" text="" readOnly="false" valueList="" displayList="" activeWhen="">
  <valueRequired>false</valueRequired>
</control>

NB: to retrieve all the parameters of the targetProperty (MDX, FILTERNAMES, FILTERVALUES, TITLE, ... ) , you just have to first run the native Excel Export and then copy the link by using the Downloads view of your browser.

WARNING : the targetProperty length is limited to 250 characters