@Carl Love Yes, actually I want that part. Can you explain what this command is doing?
Did you read the "Rephrasing my prolem" mentioned above?

@Carl Love
Consider that you have a complicated expresstion strored in f. You have to use a command like "factor(f)" or "simplify(f,size)" to make the big expression in f small and simplified. Then, f takes the form of f=(x+y)*(a+b). The nest step is that you want to choose the (a+b) part of f. Unfotunately as you mentioned the "Op" command will not work since the oprand numbers change during different runs. what should we do? (Of course I know that the devision by (x+y) will do it! :D)

@Carl Love Here is my code. I will be so thankful if you show me a way to make the operand numbers definite in this situation. The last line in the code containing the op command is important for me.

Op.mw

@Preben Alsholm 
Thanks. It works.
Is there any other way not working with the operands directly?
The reason that I am asking for such a way is that I should work with bigger expressions like below!

@Markiyan Hirnyk 
You are right! It was a question! I am new here so pardon me for the mistake! :)
Thanks for the answer! it works!

As I understood it seems the integration works with "Sum" which in an inert function but doesn't work with "sum" which is an active function! Is this reasonable or it is a bug!! :/

Thanks for the attention Carl ! but I already knew that!
I prefer to write my codes in the main window.It seems funny because for
every execution group you must creat a code edit region and for long codes it doesn't
really look good !
I don't know that why maplesoft hasn't solved this simple problem since maple 11 !

wow christopher ! you saved me !
this tabbing nuisance was driving me crazy !
the hotkeybind thing worked out !
thank you!
I am really happy now!
:))))

but I don't know why maple soft hasn't fixed this simple problem since maple 11!!!!
maplesoft please fix this problem for god's sake !
It's not a big deal!

wow christopher ! you saved me !
this tabbing nuisance was driving me crazy !
the hotkeybind thing worked out !
thank you!
I am really happy now!
:))))

but I don't know why maple soft hasn't fixed this simple problem since maple 11!!!!
maplesoft please fix this problem for god's sake !
It's not a big deal!

@John :

Hi there! :)
I am a beginner with maple. I have started using it with maple 15. The very first problem I encountered while writing codes was this tabbing nuisance. So I googled for the problem and I saw your posts since 2007 till 2010. I want to know that did you finally solve the problem?

Here is my problem :
I tried to write the code below.

for a from 1 to 4 do
	print (a):
end do:

I write down the first line and then I press shift+enter to come to the second line. then I press 
the tab key for the indentation. the cursor moves forward and everything seems good but when
I want to start to write the second line it starts from the begining of the line !
It is making me crazy! please help me!