I was quite confused that this wasn't a feature, since it happens automatically in all Smartsheet's "how-to" animation videos. I spent ages trying to work out why my header rows weren't automatically colouring :)
Can we please have the ability to allow cond. formatting to apply to the gantt bars for parent tasks, thus being able to show when a group of child tasks is complete the parent task bar also changes to your chosen colour. This will mean you can collapse the parent and still show that it has been fully completed on the gantt.
Allow conditional formatting to be applied on parent rows and Gantt Charts