Resizable: corner handles should be larger

[scott.gonzalez]

The corner handles, e.g., north-west handle, are square and therefore are either too small or extend into the content area.

See  shedokan's image of how the handles should work.

[joern.zaefferer]

Something to consider for 2.0.0 rewrite. Though I doubt that its a good idea to make the handles even smaller. There's a reason why windows on OSX have a single, somewhat large handle and no single-pixel line handles.