I am using Gridster v0.7.0, Recently I am facing one problem that while dragging the widgets the dragged widget gets overlapped on the widget that exists on that co-ordinates.
Below I have attached the GIF for better understanding.
Gridster Overlapping GIF :
1.
2. 
Adding the code for creating Gridster.
gridster = $("#GDashboard ul").gridster({
namespace: '#GDashboard',
widget_margins: [10, 10],
widget_base_dimensions: [270, 126],
max_cols: 4,
extra_rows:15,
avoid_overlapped_widgets: true,
serialize_params: function ($w, wgd) {
return {
id: $w.attr('id'),
col: wgd.col,
row: wgd.row,
size_x: wgd.size_x,
size_y: wgd.size_y
};
}
}).data('gridster');
You can add new grids by using the builtin option
gridster.add_widget('<li class="new">The HTML of the widget...</li>', 2, 1);this will probably solve your overlap issue