Firstly thanks for a great plugin.
I have found that if I place a map control in the bottom left position then the resize control is displayed above this control so that one cannot click on it.
On inspection I see your css has the statement z-index: 1000.
Other controls seem to be set with z-index 800
As the resize control at the bottom extends to the left and right of the map I have had to set the z-index to 750 so that the bottom left control works.
I hope this makes sense.
I don't know if my solution is a good one or could the bottom resizer be smaller in width.
Not sure if you are still supporting this project but in case you are it would be good to be able to supply a minimum size for the map so the user cannot resizer to a smaller size than this.