Is your feature request related to a problem? Please describe.
When the user clicks a <DeleteButton> in an Edit toolbar, react-admin displays "Element deleted". I would like to customize that message for different resources (e.g. "Post deleted" and "Comment deleted").

Describe the solution you'd like
I would like DeleteButton to behave like SaveButton and accept onSuccess and

hi, after hide columns still show up in columnsButton.

i hide some columns in my table using hidden:true also the show up disabled but still there, have some way to hide columns from there?

and also i have space between index and name columns after hide column

• The issue is present in the latest release.
• I have searched the [issues](https://github.com/mui

In the serverside-pagination example, we have some sample means of adding loading indicators. Loading indicators are a common and important part of the serverside experience, so we should have some better examples here so that other devs can work from good ideas, and we can keep full-fledged loading indicator options out of the core library (E.g. gregnb/mui-datatables#958

Add focusRectSizeFactor parameter for rectangle focus shape (like focusCircleRadiusFactor for circular). Default value should be 1.

IconButton does not 'blur' when it loses focus, retaining it's --background-focused class after the mouse or touch leaves the item.

First of all, thanks for your library mui-treasury.

I would like to change the background color of an InsetSidebar but I can't figure out how to proceed.

Here is part of my code:

<InsetContainer rightSidebar={
                    <InsetSidebar
                      sidebarId={"appPageDrawer"}
                      classes={{ paper: styles.pageDrawer }}
                    >
...