🎁 The Data Grid headers have been refactored to bring immense improvements to scrolling, state management, and overall performance of the grid.
⚙️ The Data Grid disabled column-specific features like filtering, sorting, grouping, etc. could now be accessed programmatically. See the related docs section.
🚀 Uplift the Simple Tree View customization examples (#11424) @noraleonte
🌍 Add Croatian (hr-HR), Portuguese (pt-PT), and Chinese (Hong Kong) (zh-HK) locales (#11668) on the Data Grid @BCaspari
🐞 Bugfixes
💔 Bump @mui/material peer dependency for all packages (#11692) @LukasTy The minimum required version of @mui/material is now 5.15.0.

Data Grid

Breaking changes

The ariaV7 experimental flag has been removed and the Data Grid now uses the improved accessibility implementation by default. If you were using the ariaV7 flag, you can remove it from the experimentalFeatures prop:
```
-<DataGrid experimentalFeatures={{ ariaV7: true }} />
+<DataGrid />
```
The most notable changes that might affect your application or tests are:
- The role="grid" attribute along with related ARIA attributes are now applied to the inner div element instead of the root div element:
```
-<div class="MuiDataGrid-root" role="grid" aria-colcount="5" aria-rowcount="101" aria-multiselectable="false">
+<div class="MuiDataGrid-root">
   <div class="MuiDataGrid-toolbarContainer"></div>
-    <div class="MuiDataGrid-main"></div>
+    <div class="MuiDataGrid-main" role="grid" aria-colcount="5" aria-rowcount="101" aria-multiselectable="false"></div>
   <div class="MuiDataGrid-footerContainer"></div>
 </div>
```
- When the Tree data feature is used, the grid role is now role="treegrid" instead of role="grid".
- The Data Grid cells now have role="gridcell" instead of role="cell".
- The buttons in toolbar composable components GridToolbarColumnsButton, GridToolbarFilterButton, GridToolbarDensity, and GridToolbarExport are now wrapped with a tooltip component and have a consistent interface. To override some props corresponding to the toolbar buttons or their corresponding tooltips, you can use the slotProps prop. Following is an example diff. See Toolbar section for more details.
```
  function CustomToolbar() {
    return (
      <GridToolbarContainer>
      <GridToolbarColumnsButton />
      <GridToolbarFilterButton
  -     title="Custom filter" // 🛑 This was previously forwarded to the tooltip component
  +     slotProps={{ tooltip: { title: 'Custom filter' } }} // ✅ This is the correct way now
      />
      <GridToolbarDensitySelector
  -     variant="outlined"    // 🛑 This was previously forwarded to the button component
  +     slotProps={{ button: { variant: 'outlined' } }} // ✅ This is the correct way now
      />
      </GridToolbarContainer>
    );
  }
```
Column grouping is now enabled by default. The flag columnGrouping is no longer needed to be passed to the experimentalFeatures prop to enable it.
```
-<DataGrid experimentalFeatures={{ columnGrouping: true }} />
+<DataGrid />
```
The column grouping API methods getColumnGroupPath and getAllGroupDetails are no longer prefixed with unstable_.
The column grouping selectors gridFocusColumnGroupHeaderSelector and gridTabIndexColumnGroupHeaderSelector are no longer prefixed with unstable_.
The disabled column specific features like hiding, sorting, filtering, pinning, row grouping, etc could now be controlled programmatically using initialState, respective controlled models, or the API object. See the related docs section.

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