It's not possible to access the textbox with a single or double click, when the shape containing a textbox is selected. You have to deselect the shape first and click into to textbox of the shape. At the opposite a textbox can accessed already only by typing something
Steps to Reproduce:
1. Open the attached file
2. Select the shape
3. Try to enter the textbox within the shape, without deselecting it first (not working)
4. Type something: "AA"
The textbox within the shape can't be easily accessed after the shape is selected
Easy access to the shape by single or double clicking into the textbox zone. Eventually block adding text by typing (if the shape is selected). Pressing a key could happen by accident.
User Profile Reset: No
Build ID: 274ecb49b70b3f01d47546e3b44317946c106042
CPU threads: 4; OS: Windows 6.2; UI render: default;
TinderBox: Win-x86@62-TDF, Branch:MASTER, Time: 2017-05-05_22:45:07
Locale: nl-BE (nl_NL); Calc: single
User-Agent: Mozilla/5.0 (Windows NT 6.2; WOW64; rv:45.0) Gecko/20100101 Firefox/45.0
Created attachment 133136 [details]
When the shape is in selection mode you likely want to move it around. If the focus is somewhere else you can easily enter the edit mode - and per escape go back to selection. In any case the shape selection is possible per click on the border of the shape.
The alternative solution is how Draw handles this. Single click selects the object, double click enters it. That's also true for text boxes: single click selects, another double click enters. Feels less intuitive to me but would be consistent.
Another idea is have larger zones on the object, i.e. when the user clicks at the space where usually text is entered the edit mode is enabled and otherwise the selection mode. That has to be accompanied with good feedback in terms of an appropriate cursor.
Checked again with your example. The text box always receives keyboard input. Furthermore escape toggles between shape and textbox selection. So while the interaction is not really intuitive it is a WFM.