New GD Products Center 1.2 no longer includes comparison basket widget, and instead you have Compare Box. This is not sidebar related control, and it can be placed anywhere on the page. Plugin has own methods for adding it to the page, but you can change that.
Plugins settings for compare box are these:
First option will make sure that compare box is automatically added to singe product and products archives pages. If you want to manually add compare box using function, disable this option. Empty on Compare, when enabled will empty compare box when you click on Compare. Controls for compare box can be displayed as Normal or Compact (affects buttons size and labels). And you can choose how the products are displayed in the box with Products Layout option.
To add compare box somewhere else on the page, use this function: gdpc_compare_box_embed(). You don’t need to supply product type name for this function, it will attempt to detect it based on current page. If that can’t be done, compare box can’t be displayed.