EventSystem losts selected

I have a panel and 2 buttons on this panel. I set ButtonA as selected. when i touch or click on the empty area of the panel EventSystems resets selected. How can i prevent panel to reset selected item of EventSystem?

 

You can do EventSystem.SetSelectedGameObject if you select an undesired object. Or you can have a custom interface to interact the way you want to.
Lets say you click on a button, you can use the eventsystem selected to detect that, and your custom handler to have a selectables list (could be based on layers or tags) and only change the Selected gameobject if it is part of that list.
You could also force re-selecting the last object when you click on an area you do not desire to select.

 

so I have to check and change it manually. is it right?