Some annoying Replace window

[Setzer]

I'm trying to develop a Text Editor. And I'm stuck here: I have a replace box wich replace a word with another( the words are specified by the user).I'm using the standard replace box. But if the replacing word has more or less letters than the word to be replaced, the text is replaced exactly as it is( e.g. if I try to replace the word "smoking" with "programming in the phrase "smoking is fine", I get "programmingfine" instead of "programming is fine"

 

[2ffat]

Post a snippet of code.
James P. Cottingham

I am the Unknown lead by the Unknowing.
I have done so much with so little
for so long that I am now qualified
to do anything with nothing.