CMYK color may be set using SCN, scn, K and k operators.

Available support for import of CMYK colors in R3 2018 Official Release.

Square annotation displays a rectangle on the page. When opened, it displays a pop-up window containing the text of the associated note.

The issue may be reproduced by opening the attached PDF in Adobe Reader. Although the viewer initially shows the characters correctly, when you start typing in the TextBox, the umlaut/diacritics characters get corrupted. In other PDF viewers, the umlaut characters are handled correctly, so the issue seems to related to concrete Adobe Reader encoding handling implementation. The diacritic characters are handled incorrectly in other viewers as well (e.g. Chrome).

Text fields should support rich text strings allowing the user to use rich text elements and attributes.

Provide a way to change the Name of a FormField from the RadDocument.AcroForm.FormFields collection.

As a workaround, you could create a new instance of a FormField with the desired name, add the new field in the document and remove the old one. You can use the following approach:
   1) Create a new instance of FormField (with the desired name, passed in the constructor), which will play the role of a copy of a specific FormField
   2) Copy all properties from the original field (they all vary, depending on the concrete type of the FormField, for example CheckBoxField, etc.)
   3) Create a new widget for the new field, and copy all properties from the original field's widget into the new one.
   4) Remove the original field from the RadDocument.AcroForm.FormFields collection and add the new field.
   5) Remove the original widget from the corresponding page's annotation and add the new one.

Attached is a project demonstrating this approach for a CheckBoxField.

Currently, a default constant value is used for the font size in this scenario.

For instance, we may implement WritePageAsync method in addition to the existing WritePage method. This is a similar scenario as in System.IO.StreamWriter class which has WriteLine and WriteLineAsync methods.

CryptographicException is thrown when saving with PdfStreamWriter or importing with PdfFormatProvider.

The exception: System.Security.Cryptography.CryptographicException: 'The input data is not a complete block.'

According to the PDF specification:
A clipping path operator (W or W*) may appear after the last path construction operator and before the path-painting operator that terminates a path object.

Invalid:

W                          % clipping path operator
0 0 m                     % start of the path construction
596 0 l
596 842 l
0 842 l
h                            % end of the path construction
n                            % path-painting operator

0 0 m
596 0 l
596 842 l
0 842 l
h
W
n

Currently (in the invalid cases), the path construction is skipped on import.