Hi guys!
This is actually a new feature in the Axure RP 9 Beta, where we introduced single-key shortcuts, which you can read more about below:
https://www.axure.com/blog/new-in-axure-rp-9-single-key-shortcuts/
That is, you can now click-drag to produce a shape after clicking on any of the mentioned shortcut keys:
R – rectangle mode
O – oval / ellipse / circle mode
T – text mode (drag to dynamically fill area with example text)
P – pen drawing mode
L – line mode
One additional thing that may help is hitting [enter] to type in the widget, if you wanted to stay in single-key mode. 
However, if you would like to restore the older, default behavior (as in Axure RP 8), you can go to “Axure RP 9 Beta > Preferences > Canvas” from the main menu, and de-select the “Enable Single Key Shortcuts” checkbox:
This will allow you to select a widget and start typing text to enable text-editing mode for that widget.