Opacity mask
You can use opacity mask to hide part of widget. Mask is a grayscale image, so black areas are hidden, white areas are visible, and shades of gray areas appear in various levels of transparency.
To add opacity mask:
- Select widget
- Open Style Inspector
- Click Mask image in Mask section and select image file
- Select image fill mode from the list
To remove opacity mask image click — button on the right.