And want to know, there is any idea of select the table cell only and set the text align of the cell?
There is no GraphObject for each cell of a Table Panel. There is just an area where there might be zero or more objects.
The other way to look at it is that only an instance of TextBlock will have the TextBlock.textAlign property.
But a click on an object could be highlighted, and your code could operate on that object. For example:
Thank you, I will research it.