I agree, 
```javascript
minSize = minSize || 100;
```
seems to be safer but I believe that
```javascript
minSize = minSize || 0;
```
is a more general design. Furthermore, if the default value is 100 it is not posible to hide elements (e.g. the side panel) because:
```javascript
0 || 100 => 100
```
So I think the default value should be 0.

(I'm new here and want to learn so I am open to any solution)