At this point, the justify alignment is not supported. Provide the ability to export text with this setting.

Add support for shapes, and especially for shapes with textual content. 
In OOXML, shapes are represented by the wps:wsp element, and shapes with textual content by <wps:txbx>, <w:txbxContent>.
Such shape can be added to a Word document using the Insert -> Text -> Text Box -> Draw Text Box, or through a shape's context menu -> Add Text.

Do not confuse these shapes with Text/Rich Text content controls (see https://feedback.telerik.com/Project/184/Feedback/Details/190057 )

With the current implementation of the RadFlowDocumentEditor`s CharacterFormatting.FontWeight.LocalValue accepts only FontWeights.Bold and FontWeights.Normal and throws an exception when setting different weights (ex. Black, Thin, etc.).

Introduce Run.IsHidden property or similar, which hides the text in the document.

In MS Word, text is hidden using the Home -> Font -> Font -> Effects -> Hidden. In the Rtf format, such text is preceded (marked) with a '\v' tag. In OOXML, the tag is <vanish/>. The display: none; style from HTML is mapped to hidden text when document is converted to DOCX.

Hidden text is visualized with dotted underline when formatting symbols are shown. Hidden text is not exported to PDF.

Currently, the text is exported but the strikethrough line is not drawn in the exported PDF.