Steps to reproduce: 

1. Enter in a cell =Today()
2. Show Format Cells dialog and set Custom format "d"

Expected: The value is the day of the month.
Actual: The date is formatted as short date but has to be day of the month.

The label of the field that allows you to set the ScreenTip in the Hyperlink dialog is not vertically centered to the associated textbox visual. This reproduces in the Windows11 theme.

To work this around, get the TextBlock element in the Hyperlink dialog and set its VerticalAlignment property to Center.

private void RadSpreadsheet_Loaded(object sender, RoutedEventArgs e)
{
    var hyperlinkDialog = this.spreadsheet.ActiveWorksheetEditor.Dialogs.HyperlinkDialog as HyperlinkDialogContent;
    hyperlinkDialog.Loaded += HyperlinkDialog_Loaded;
}

private void HyperlinkDialog_Loaded(object sender, RoutedEventArgs e)
{
    var dialog = (HyperlinkDialogContent)sender;
    var screenTipLocalizedText = LocalizationManager.Manager.GetStringOverride("Spreadsheet_InsertHyperlinkDialog_ScreenTip");
    var screenTipTb = dialog.ChildrenOfType<TextBlock>().FirstOrDefault(x => x.Text == screenTipLocalizedText);
    if (screenTipTb != null)
    {
        screenTipTb.VerticalAlignment = VerticalAlignment.Center;
    }            
}

#.##0,00;-#.##0,00;;@ does not work in RadSpreadsheet. It should suppress visualizing of ) values.

Workaround: #.##0,00;-#.##0,00; ;@ works fine (there is ' ' [space] set for the zero values).

When setting the following strings as cell value, they are recognized as dates. In industry standard applications like MS Excel and OpenOffice, they are recognized as strings:
- "12 3456" in bg-BG, fr-FR, ru-RU, sv-FI, en-US
- "12.3456" in de-DE
- "1 23" in en-US
- "2013/5" in en-US
- "3000-03" in en-US

Steps to reproduce:
- Open RadSpreadsheet
 -Put 1 in B2 and B6
 -Put 0 in B3, B4, B5
 -Add filtering on columns A and B
 -Filter on column B to have only rows with 1. The rows 3 to 5 will be hidden.
 -Paste "1234" as cell selection in the Range A2:A6 
 Note: It is important to enter 1234 in another cell, make a cell selection and then paste it
 -Remove the filter

Expected: "1234" in pasted in cells A2 and A6 only.
Actual: "1234" in pasted in cells A2, A3, A4, A5, A6.

Selecting a column with two or more merged cells, selects not only the selected column but the rest of columns that the merged cells are from. The behavior when working with rows is analogical.

The fill selection stops working, after a filtering is applied and the currently selected cell is filtered out (it gets hidden). This prevents from displaying the fill selection cross displayed when you hover the bottom right corner of a selected cell. Any further changes in the selection doesn't re-enable the selection fill feature.

To work this around, you can set the IsEnabled property of the FillSelection on selection changed.

private RadWorksheetEditor activeWorksheetEditor;

public MainWindow()
{
  InitializeComponent();

  this.spreadsheet.ActiveSheetEditorChanged += (s, e) =>
  {
 if (activeWorksheetEditor != null)
 {
 activeWorksheetEditor.Selection.SelectionChanged -= Selection_SelectionChanged;
 }

 activeWorksheetEditor = this.spreadsheet.ActiveWorksheetEditor;
 activeWorksheetEditor.Selection.SelectionChanged += Selection_SelectionChanged;
  };
}

private void Selection_SelectionChanged(object? sender, EventArgs e)
{
  this.spreadsheet.ActiveWorksheetEditor.Selection.FillSelection.IsEnabled = true;
}

Returns a Range object that represents the current region. The current region is a range bounded by any combination of blank rows and blank columns. If we want to be consistent with MS Excel we should implement this property. It is useful for many operations of a region such as filtering(selecting one cell and executing the Filter command should apply it to the current region), sorting, selecting all and etc. This document will be useful: https://docs.microsoft.com/en-us/office/vba/api/excel.range.currentregion.

Check how the performance can be improved in this scenario. The StyleGallery is taking much time to load, the GetUsedCellRange method is called multiple times.

The numeric box that allows you to select the "to" page in the PrintPreviewControl is clipped when the "Pages:" and "to" strings are translated to a language where these words are longer. For example, this reproduces with Dutch culture which uses the "Pagina's:" and "naar" texts.

To work this around, you can get the Grid panel that hosts the content and increase the Width of one of its ColumnDefinitions.

  private void PrintPreviewControl_Loaded(object sender, RoutedEventArgs e)
  {
      var printPreview = (PrintPreviewControl)sender;
      var rootGrid = printPreview.FindChildByType<Grid>();
      rootGrid.ColumnDefinitions[0].Width = new GridLength(355);
  }

Add an event that indicates when a hyperlink is clicked.