Hello,

I'm using media queries with zoom property and it's confusing cell selection within the canvas.

Here's a snippet to replicate the case:
```

var grid = new fin.Hypergrid('#fin-grid', {
data: [
{ 'symbol':'APPL', 'name':'Apple Inc.', 'prevclose':'93.13' },
{ 'symbol':'MSFT', 'name':'Microsoft Corporation', 'prevclose':'51.91' },
{ 'symbol':'TSLA', 'name':'Tesla Motors Inc.', 'prevclose':'196.40' },
{ 'symbol':'IBM', 'name':'International Business Machines Corp', 'prevclose':'155.35' }
]
});



```
To select the first data row, you need to have the cursor on the third data row. Horizontal offset can also be affected with a more complex setup.
It would seem that this.canvas.getBoundingClientRect() does not return an accurate ClientRect anymore.
Any idea how to cope?