If you set "[h]:mm" as a custom format to a cell which has time set to it the calculated value in the cell is wrong for the minutes. The minutes part is interpreted as months.

The number format [hh]:mm causes ArgumentException on import.

Borders can overhang 1 px from the corresponding cells. The issue is reproducible only on some zoom levels, and is most probably related to WPF layout rounding. The issue is mostly visible when borders are missing. 

On different zoom levels, different borders are hanging.

ArgumentException is thrown ("Error: Argument1" message box in case of importing through RadSpreadsheet) when importing document containing cell with applied custom data validation rule restricting the value of the cell to empty values only - '""' (two double quotes).

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.

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.

When the PrintPreview has to show many UIElements at once, the performance is slow.

This behavior happens at a specific width of the cell's Column. Using different VerticalAlignment (not Bottom) would workaround this issue.

The exception is thrown when the color for the borders has been previously set using the colors from the predefined palette. The next attempt to set a border color using the ShowMoreColorsDialog leads to error. A message appears to the user saying "Specified cast is not valid".

When the users click on the More Borders option provided in the ribbon UI, the Format Cells dialog opens but the popup of the dropdown is still kept open.

When the InsertFunctionDialog is opened and the "Go" button is pressed with many words entered in the search terms field, the performance is so slow that the application appears hanged.

When the size of the columns is changed using the ColumnSelection.SetWidth(*) method does not update the layout, so subsequent uses of the layout are not calculated correctly. For example BringIntoView method works incorrectly. 

Workaround: call RadSpreadsheet.UpdateLayout() after setting the width.

Cell borders below the cells filled with data are not exported to XLSX.

When filtering a big range of values, the performance is low. The whole UI is re-created.

An ArgumentNullException is thrown when you try to open a document containing relationship namespace declared in the tag.

<sheet name="Management Position View" sheetId="1" d3p1:id="rId1" xmlns:d3p1="http://schemas.openxmlformats.org/officeDocument/2006/relationships" />

The exception is thrown in the QuarterAutoFillGenerator TryParse method due to the unexpected length of the value.

Workaround: Do not use SetValueAsText method by passing an empty string to it. Use SetValue or ClearValue instead.

When a sheet that has a new line in a text value is exported and the resulting file is opened in Excel, the value is displayed without a new line. If you enter edit mode and then exit (without confirming the value by pressing enter) the new line will appear. The reason for this behavior is that when there is a new line in a text value Excel automatically applies wrap text on the cell while RadSpreadsheet does not do that. A possible workaround is to apply wrap text on new values with new line in them.

When a row is removed through code and an image is created immediately after that in the same method, the UI does not update. The change is made in the model, but not visualized. If you scroll up and down the change is reflected in the UI.

When trying to set the VisibleSize property of RadSpreadsheet on the ActiveSheetChanged event a null exception is thrown in the UpdateSheet method of RadSheetEditorBase. 

Possible workaround is to record the visible size at the SheetChanged event and set it at a later time, e.g. using a timer.

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.