Forms :: Making A Spell Checker For Richtextbox Control

i'am having trouble in making a spell checker for vb.net richtextbox control.I have made a form with richtextbox control and a panel control. I have put a listbox control in the panel control and filled with certain words. What iam able to do is whenever i select a word and click a button the panel appears just below the word (using get position from char) and display the choice. What iam not able to do is:

1) Select each word one-by-one whenever i click a button say F1 - I know keypress event but how do i select the words through keypress. I know they are separated by spaces but iam not familiar as to how to take advantage of it. The major problem being that there can be 2-3 words together sometimes colored as red. Eg: What i want is when i press F1 first time "this" is selected, next time "is" is selected and next time "nice car color" is selected. The two things are spaces and red color but i don't get anything from it.

2) Display the panel correctly within the main form's border. Right now when i select the last word of the sentence some part of panel disappears as it hides behind the main form. Eg - only 1/4th appears and rest hides. I can't find a way to limit it from moving when it has reached the main form size. I want to constrain it between top-bottom and left-right border of main form.