I encountered the same problem, while trying to create an animation loop for a gridster dash.
I have added a new function to the gridster src, which is basically just a very simple rewrite of the resize_widget API function. This in itself just uses mutate_widget_in_gridmap as pointed out by @Pavel.
I added the following after Resize_widget function:
fn.move_widget = function($widget, new_col, new_row, callback) {
var wgd = $widget.coords().grid;
var new_grid_data = {
col: new_col,
row: new_row,
size_x: wgd.size_x,
size_y: wgd.size_y
};
this.mutate_widget_in_gridmap($widget, wgd, new_grid_data);
this.set_dom_grid_height();
this.set_dom_grid_width();
if (callback) {
callback.call(this, new_grid_data.col, new_grid_data.row);
}
return $widget;
};
Works like a charm for me. Tell me if you can come up with a good way to smooth the transition with JQuery or something :)