Printer's marks provide useful information when printing professionally, for example indicating the edge of the document so that it can be cropped to the proper size after printing.
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To apply the marks select Commerical PDF from the Download > PDF menu and then check the box.

You'll see the marks when you open up the downloaded PDF. 

Additionally, if you have the crop marks setting applied and you select the Print option instead of Download then your PDF will still appear with the crop and bleed marks.

You can now use the line width setting to set a border/line width on a text area. When you apply the setting to a simple text area it is transformed into a text panel adding SmartShape functionality. 

Select the area and enter a value in the Line box on the properties panel...   

Now you can easily change between text areas and text columns using the new Fixed height option on the Text Properties panel.

When checked, the text item appears as a text area with a defined height and the vertical alignment and auto-fit options enabled. When not checked, the text object will appear as a text column with the vertical alignment and auto-fit options disabled.

Note that the option will not appear for grouped objects or SmartShapes.