All you have to do is just go here (I wouldn't do this if you had a non-responsive theme as it's not worth, but if you had a responsive theme like myself, then go ahead and do this as it makes the reaction adding panel responsive. )
Home » Template Sets » Global Templates » Edit Template: myreactions_react
And Replace the first line with following.
Home » Template Sets » Global Templates » Edit Template: myreactions_react
And Replace the first line with following.
Code:
<div class="modal" style="height: 80%;width: 70%;overflow: scroll;margin-left: -468.5px;">