Solved it using Girder. (
http://www.girder.nl)
A new screen for the radio was added. When opening this screen a command is send to girder to check wether the radio is already open. If not, open the radio, if it is open, set focus to the radio. As Xlobby stays in front after I've set focus to the radio (radio stays second) I send an extra OS command from girder "task switcher" which is the same as using Alt Tab, so now it is in front.
I added the girder command below. To test copy it into file and rename radio.GML. THe girder program should be installed
<?xml version="1.0" encoding="UTF-8"?>
<Girder><Group Name="Radio" Identifier="6941" Enabled="TRUE"><MultiGroup Name="ShowRadio" Identifier="6938" Enabled="TRUE"><StateCount>1</StateCount><StateBegin>1</StateBegin><StateCurrent>1</StateCurrent><StateInvert>FALSE</StateInvert><Command Name="CheckRadio" Identifier="6949" Enabled="TRUE"><Comments>Controleer of de radio al geopend is of dat deze nog moet worden geopend</Comments><StateCount>1</StateCount><StateBegin>1</StateBegin><StateCurrent>1</StateCurrent><StateInvert>FALSE</StateInvert><OSD>FALSE</OSD><Target_name>TerraTec ActiveRadio</Target_name><Target_class>#32770</Target_class><Target_exe>TTRADIO.EXE</Target_exe><CTarget_class>Button</CTarget_class><Submatch>FALSE</Submatch><Topmost>FALSE</Topmost><MatchBy>7</MatchBy><OneMatch>FALSE</OneMatch><UseVar>FALSE</UseVar><MatchHidden>FALSE</MatchHidden><MatchNum>1</MatchNum><ActionType>4</ActionType><ActionSubType>13</ActionSubType><bValue1>FALSE</bValue1><bValue2>FALSE</bValue2><bValue3>FALSE</bValue3><lValue1>6979</lValue1><lValue2>6980</lValue2></Command><EventString Name="EventString" Identifier="6967" Enabled="TRUE" Invert="FALSE" Device="18" IrStr="RadioTonen"></EventString></MultiGroup><Command Name="CloseRadio" Identifier="6966" Enabled="TRUE"><StateCount>1</StateCount><StateBegin>1</StateBegin><StateCurrent>1</StateCurrent><StateInvert>FALSE</StateInvert><OSD>FALSE</OSD><Target_name>TerraTec ActiveRadio</Target_name><Target_class>#32770</Target_class><Target_exe>TTRADIO.EXE</Target_exe><Submatch>FALSE</Submatch><Topmost>FALSE</Topmost><MatchBy>7</MatchBy><OneMatch>FALSE</OneMatch><UseVar>FALSE</UseVar><MatchHidden>FALSE</MatchHidden><MatchNum>1</MatchNum><ActionType>1</ActionType><ActionSubType>5</ActionSubType><bValue1>FALSE</bValue1><bValue2>FALSE</bValue2><bValue3>FALSE</bValue3><EventString Name="EventString" Identifier="6968" Enabled="TRUE" Invert="FALSE" Device="18" IrStr="RadioSluiten"></EventString></Command><MultiGroup Name="RadioForeground" Identifier="6979" Enabled="TRUE"><StateCount>1</StateCount><StateBegin>1</StateBegin><StateCurrent>1</StateCurrent><StateInvert>FALSE</StateInvert><Command Name="CenterRadio" Identifier="6951" Enabled="TRUE"><StateCount>1</StateCount><StateBegin>1</StateBegin><StateCurrent>1</StateCurrent><StateInvert>FALSE</StateInvert><OSD>FALSE</OSD><Target_name>TerraTec ActiveRadio</Target_name><Target_class>#32770</Target_class><Target_exe>TTRADIO.EXE</Target_exe><Submatch>FALSE</Submatch><Topmost>FALSE</Topmost><MatchBy>7</MatchBy><OneMatch>FALSE</OneMatch><UseVar>FALSE</UseVar><MatchHidden>FALSE</MatchHidden><MatchNum>1</MatchNum><ActionType>1</ActionType><ActionSubType>11</ActionSubType><iValue1>160</iValue1><iValue2>160</iValue2><bValue1>FALSE</bValue1><bValue2>FALSE</bValue2><bValue3>FALSE</bValue3></Command><Command Name="SetFocusRadio" Identifier="6953" Enabled="TRUE"><StateCount>1</StateCount><StateBegin>1</StateBegin><StateCurrent>1</StateCurrent><StateInvert>FALSE</StateInvert><OSD>FALSE</OSD><Target_name>TerraTec ActiveRadio</Target_name><Target_class>#32770</Target_class><Target_exe>TTRADIO.EXE</Target_exe><Submatch>FALSE</Submatch><Topmost>FALSE</Topmost><MatchBy>7</MatchBy><OneMatch>FALSE</OneMatch><UseVar>FALSE</UseVar><MatchHidden>FALSE</MatchHidden><MatchNum>1</MatchNum><ActionType>1</ActionType><ActionSubType>6</ActionSubType><bValue1>FALSE</bValue1><bValue2>FALSE</bValue2><bValue3>FALSE</bValue3></Command><Command Name="BringRadioToFront" Identifier="6981" Enabled="TRUE"><Comments>Omdat set focus Xlobby toch op voorgrond houd, wordt dit commando gegeven</Comments><StateCount>1</StateCount><StateBegin>1</StateBegin><StateCurrent>1</StateCurrent><StateInvert>FALSE</StateInvert><OSD>FALSE</OSD><Target_name>Program Manager</Target_name><Target_class>Progman</Target_class><Target_exe>EXPLORER.EXE</Target_exe><Submatch>FALSE</Submatch><Topmost>FALSE</Topmost><MatchBy>7</MatchBy><OneMatch>FALSE</OneMatch><UseVar>FALSE</UseVar><MatchHidden>FALSE</MatchHidden><MatchNum>1</MatchNum><ActionType>2</ActionType><ActionSubType>18</ActionSubType><bValue1>FALSE</bValue1><bValue2>FALSE</bValue2><bValue3>FALSE</bValue3></Command></MultiGroup><MultiGroup Name="OpenRadio" Identifier="6980" Enabled="TRUE"><StateCount>1</StateCount><StateBegin>1</StateBegin><StateCurrent>1</StateCurrent><StateInvert>FALSE</StateInvert><Command Name="Open_Radio" Identifier="6947" Enabled="TRUE"><StateCount>1</StateCount><StateBegin>1</StateBegin><StateCurrent>1</StateCurrent><StateInvert>FALSE</StateInvert><OSD>FALSE</OSD><Target_name>TerraTec ActiveRadio</Target_name><Target_class>#32770</Target_class><Target_exe>TTRADIO.EXE</Target_exe><Submatch>FALSE</Submatch><Topmost>TRUE</Topmost><MatchBy>7</MatchBy><OneMatch>FALSE</OneMatch><UseVar>FALSE</UseVar><MatchHidden>FALSE</MatchHidden><MatchNum>1</MatchNum><ActionType>2</ActionType><ActionSubType>14</ActionSubType><sValue1>C:\Program Files\TerraTec\Cinergy 600 TV\ActiveRadio\TTRadio.exe</sValue1><iValue2>10</iValue2><bValue1>FALSE</bValue1><bValue2>FALSE</bValue2><bValue3>FALSE</bValue3></Command></MultiGroup></Group></Girder>