Here Solution of Many Problems like it regarding of Textbox error message Hide and Lose/Hide Focus 
1st Question :
2nd Question :
3rd Question :
Here Solutions Start [With & Without Use of Extension] : 


Without Use of Extension : 
Now No Any Method Without Using of Extension. 

With Use of Extension :
1st Solution :
2nd Solution :
And many more, (Anyone Can also add here more Solution/discussion Pages/links/references etc.)
I Hope its help everyone to whose want to set Hide/Reset/Remove a textbox error message and focus in your app.
Prem 