HTML Widgets; Grid control; row selector checkbox styling updated

The styling of HTML Widget Grid control row selectors has been updated.

Row selectors are shown in widgets such as Task Manager 2, Tasks folders and allow multiple rows to be selected.

The following changes have been made:

• Checkbox is no longer circular, it is now square with rounded corners
• Checkbox is slightly larger (90% size rather than 75%)
• The CheckBox in the header row, used to select all/none, is now more visible; previously it could be difficult to see