Add Button To in Image Gallery toolbar

Hi all,
I want to add a button in a panel in my own object. I was successful in adding an icon and handler in Object Editor.
I have tried all the ext js JavaScript UI Events in my own js file and only the postOpenObject gets executed, in this Object i can see tabpanel and menu items but its too big go through every items or cannot really figure out under which menu i can add my own menu button handler. All the Javascript UI is not executing

Thanks
Unni

I extended the Imagegallery js class pimcore.object.classes.data.imageGallery with all functions in my own custom js file and added my own button in between the buttons.

Hope this will help someone looking for a solution like me.