To reproduce:
Open a document that has highlighted areas.

This is not a valid PDF scenario as having appearance state requires having multi-state appearances. However, we should handle this invalid document scenario on our side so that the app does not crash with NullReferenceException.

Load a file in RadPdfViewer, select some of the text, right click and select Copy. A sample pdf file is attached.

This dialog appears when one is clicking the signature field in the document. 

Please refer to the attached gif file and sample project. When you hide the overflow button with the first pixel, although it is indicated as Visible, it is actually not shown.

Workaround: Timer timer = new Timer();

private void commandBarStrip_ItemOverflowed(object sender, EventArgs e)
{
    timer.Interval = 100;
    timer.Tick += timer_Tick;
    timer.Start();

}

private void timer_Tick(object sender, EventArgs e)
{
    timer.Tick -= timer_Tick;
    var commandBarStrip = this.radPdfViewerNavigator1.CommandBarElement.Rows[0].Strips[0];
    commandBarStrip.OverflowButton.Visibility = ElementVisibility.Visible;
    timer.Stop();
}

 Currently, the first document is loaded. 

Workaround:
Wait for the document to load before loading the new document. 

The events should provide information as to when a page is about to be rendered and when it is displayed in the control.

When there is no ToUnicode CMap, the text from the Simple Font instance should be extracted by mapping the glyph name to its corresponding charcode according to Adobe Glyph List. Additionally, the Differences array should be included in these calculations when there is custom encoding. The current implementation of RadPdfViewer makes ToString to the original char id byte value which leads to wrong characters. 

According to PDF format specification, there are three valid encoding name values (MacRomanEncoding, MacExpertEncoding and WinAnsiEncoding). There are documents that instead of skipping the optional Encoding property, are writing invalid /NULL name value in the font dictionary. Currently, in this invalid document scenario RadPdfViewer throws and catches Exception and this results in missing text content. 

We may handle this invalid document scenario by ignoring the invalid Encoding value.

How to reproduce: check the attached project

Workaround: manually unload the document before disposing the control, the attached project includes a solution

How to reproduce: check the attached video
a slight cut off can also be observed with the ControlDefault and the TelerikMetro themes

Workaround: 
CommandBarDropDownList dropDownList = this.radPdfViewerNavigator1.CommandBarElement.FindDescendant<CommandBarDropDownList>();
dropDownList.MinSize = new Size(72, 22);

The exception is thrown during "Put" operator execution.

how to reproduce: check the attached file

workaround: resize the form

To reproduce:
Print the attached document with the MS Xps printer or PrimoPDF.