Making tree box extandable vertically.

[sakshi-dhamija]

Checklist

• I indicated which issue (if any) is closed with this PR using closing keywords
• I only changed lines related to my PR (no bulk reformatting)
• I indicated the source and check the license if I re-use code, or I did not re-use code
• I made my best to solve only one issue in this PR, or explain why multi had to be solved at once.

Issue

close #157

[raashika03]

Providing some description will be nice for quick review at least.

[sakshi-dhamija]

Hi @raashika03, Yeah agreed but I have explained this pretty well in the issue I linked, and the title of the PR did the remaining work about informing. So I didn't feel the point of writing a description.

[bryan-brancotte]

Hi @secrashi

Good job ! I did not knew that the solution could be as clear as this. 🏆