The following Snippet shows, how to create a a GMENU with bold font in the rollover (RO). If you create the menu in the usual way you have the problem, that the rolloverimage looks bad because it gets shrunk as it is bigger then the orginal.

To avoid this problem you can create a hidden textobject, with the properties as the desired Object in RO. Now you know the dimensions of the RO and you can use them to calculate the size of the NO. This way the Rollover looks good :)

Here is the typoscript code

temp.gmenu=HMENU
temp.gmenu.1=GMENU
temp.gmenu.1{
  NO {
    backColor=#CCCCCC
    XY=[20.w]+20,20
    10=TEXT
    10.text.field=title
    10.fontFile=fileadmin/fonts/verdana.ttf
    10.fontSize=11
    10.fontColor=#333333
    10.offset=6,14
     
    20 = TEXT
    20.hide=1
    20.text.field = title
    20.fontFile = fileadmin/fonts/verdanab.ttf
    20.fontSize = 11
    20.offset = 6,14
  }
   
  RO = 1
  RO {
    XY = [10.w]+20,20
    10 = TEXT
    10.text.field = title
    10.fontFile = fileadmin/fonts/verdanab.ttf
    10.fontSize = 11
    10.fontColor = #333333
    10.offset = 6,14
     
  }
}

Have a look to the 20 object, there are 2 important things. First thing is the hide=1 with allows us to hide the object. The second thing is that we use the same bold font as in the rollover, this way he have the same size

View sample

More information can be found on TSRef

GMENU

GIFBUILDER