Currently Minimize\Restore\Maximize buttons are not shown in the ToolWindow's header, so there are some inconveniences in use. For example, it's impossible to minimize tool windows easily.

The document will be imported with a loss of content. The reason is that ASCII85Decoder will throw an ArgumentException when the stream doesn't end with '~>'. 

Although this is invalid case according to PDF specification, other applications are handling it and the document is successfully visualized in them. We may also consider implementing workaround that handles such invalid streams.

According to the PDF specification (Adobe® Portable Document Format Version 1.7):
Append a rectangle to the current path as a complete subpath, with lower-left corner (x, y) and dimensions width and height in user space.

The operation: 

x y width height re

An invalid case:

0 - 595 -842 re

This leads to an exception thrown: System.NullReferenceException: 'Object reference not set to an instance of an object.'

Implement the export of notes (footnote, endnote) in the PdfFormatProvider of the RadRichTextBox.

We want to have the option to replace texts only in a selected part of the document. 

Use Notepad++ as a reference to check this feature.

Currently, the InputBoxText property of the RadChat control has a read-only purpose. It is updated only when you update the text via the UI. However, the property has also a public setter which implies that it can be set, but this doesn't work. 
Allow setting the InputBoxText property, which should update the text in the input TextBox.

For the moment, you can get the RadWatermarkTextBox element using the FindChildByType<T> method and set its Text property manually.

var textBox = this.chat.FindChildByType<RadWatermarkTextBox>();
textBox.SetCurrentValue(RadWatermarkTextBox.TextProperty, "new text")

Add protection mode that allows to make the document readonly, but allow forms editing. In MS Word this can be enabled via the "Restrict Editing" menu. The option is called "Filling in forms" and protects the document, but leaves the Sdt elements (the forms) editable.