How to show thumbnail images inside a grid widget?
If you have images stored inside attachment properties and would like to be able to visualize them as a thumbnail in a basic or paginated table widget, then you need to configure your widget as such.
The following steps allow the user to configure thumbnails inside a widget:
Go to a task where such widget is configured;
Click Alt+W in order to Enable edit-mode;
Open the Configure widget dialog;
Click on the Styling tab and tick the Show thumbnails option;