How to reproduce: check the attached screenshot

Workaround create a custom RadPrintPreviewDialog
public class MyRadPrintPreviewDialog : RadPrintPreviewDialog
{
    protected override WatermarkPreviewDialog CreateWatermarkDialog()
    {
        WatermarkPreviewDialog dialog = new WatermarkPreviewDialog(this.Document);

        RadPageViewPage pageText = (RadPageViewPage)dialog.Controls["radPageView1"].Controls["pageText"];
        ((PlusMinusEditor)pageText.Controls["plusMinusEditorTextHOffset"]).TextBox.Width = 43;
        ((PlusMinusEditor)pageText.Controls["plusMinusEditorTextVOffset"]).TextBox.Width = 43;
        ((PlusMinusEditor)pageText.Controls["plusMinusEditorTextAngle"]).TextBox.Width = 43;
        ((PlusMinusEditor)pageText.Controls["plusMinusEditorTextOpacity"]).TextBox.Width = 43;
        RadPageViewPage pagePicture = (RadPageViewPage)dialog.Controls["radPageView1"].Controls["pagePicture"];
        ((PlusMinusEditor)pagePicture.Controls["plusMinusEditorImageHOffset"]).TextBox.Width = 43;
        ((PlusMinusEditor)pagePicture.Controls["plusMinusEditorImageVOffset"]).TextBox.Width = 43;
        ((PlusMinusEditor)pagePicture.Controls["plusMinusEditorImageOpacity"]).TextBox.Width = 43;

        return dialog;
    }
}