QtDesigner crash: setting CSS text color of any widget

In Qt Designer, since several versions (since I started using Qt).
It Crashes when setting some patterns of text color in the CSS.

Scenario:

• Put a QLabel into the QtDesigner
• Write a text color: color: rgb()
• Delete/Edit the values into the rgb list.

I do not have a very clear idea of which pattern crashes, but it is reproductible 100% times.