OK, had a bit of time on my hands, so tried this out.

1) Carefully copied and pasted the changes to EventList.ascx

2) Removed width="150px" from SelectCategory.ascx

3) Copied and pasted the ThemeEvents to the MyTheme file

After 2 above, the calendar on http://www.1066-ice-skating-club.org.uk/NewsEvents.aspx displays as it does now, even though I have changed:

.ThemeEvents .RadComboBox_Default {
width: 150px !important;
}

to

.ThemeEvents .RadComboBox_Default {
width:300px !important;
}

I double-checked that I was changing the MyTheme file on the correct portal and even temporarily copied the theme files to the DesktopModules > Events > Themes and changed the Calendar settings accordingly but no change.

Thoughts?

D'Oh! Changed ThemeEvents to ThemeMyTheme and now the combo box has centred and changed width but the Categories label has again moved to the top of the box. I'm not clear on what the various %'s do?