Incorrect sizing and rendering of NatCombo

[fipro78]

NatTable provides a custom control called NatCombo that is used to add a dropdown editor in NatTable. The rendering of the NatCombo looks incorrect with Evolve. To see it directly, here is the screenshot with SWT:

Here is the screenshot with Evolve:

You can see that:

• the width in Evolve seems to be derived from the cell dimensions, but actually the size, especially the width, is calculated based on the content.
• there is a strange space between "Select All" and the other entries, which should not be there.