Hi Matteo
The way I test with this plugin is to simply activate the handheld or tablet theme you’re developing as the primary theme for your website. Then I re-size my browser window down to certain dimensions, essentially pretending I’m viewing the website from any device.
You can refer to the List of common resolutions article on Wikipedia for sizes you’re looking to target.
I also use the ‘Inspect’ feature in the Firefox ‘Web Developer’ plugin to quickly ascertain what the width of my <body> tag is. So if I’m building a handheld theme, I’d re-size the browser window to 960×640 to make sure the theme looks good on iPhones, and so on with a few other common handheld sizes.
Hope that helps!
