To apply partial transparency to a ‘Mesh Filled’ object follow these steps:
a. After filling an object, click on the Mesh Fill icon in the toolbox – shortcut: [ M ].
b. Select the nodes of the area you wish to apply the transparency to.
c. Adjust the intensity of the transparency effect in the Property Bar (enter a value or slide the bar to process the setting).

See figure: note that only the selected nodes region was affected.

Tip provided by Silvio Gomes, CorelDRAW Master, Artist and Graphic Designer.