Automatically select the brush size numbers when rightclicking to open brush tool panel

[The_Dungeon_Madame]

How do I set it in my settings that the text in my brush tool panel automatically is selected (so I can begin typing right away, without having to select the numbers myself first) when I rightclick to open the panel? 

See image to see what brushtool panel + text I'm talking about. 

[Myra Ferguson]

When the text is highlighted, you can enter a value.

If the first field isn't highlighted or if you want to enter a value in another field, then you can press the Tab key to highlight the next field in the tab order.