[K.A.V.]

Так тоже не работает?

WS_DLGFRAME

Код:

 Function GUIInit
 ${NSD_RemoveStyle} $HWNDPARENT ${WS_CAPTION} 
 System::Call "user32::GetWindowLong(i$HWNDPARENT,i${GWL_STYLE})i.r0"
 System::Call "user32::SetWindowLong(i$HWNDPARENT,i${GWL_STYLE},i$0|0x00400000)" 
 FunctionEnd

WS_BORDER

Код:

 Function GUIInit
 ${NSD_RemoveStyle} $HWNDPARENT ${WS_CAPTION} 
 System::Call "user32::GetWindowLong(i$HWNDPARENT,i${GWL_STYLE})i.r0"
 System::Call "user32::SetWindowLong(i$HWNDPARENT,i${GWL_STYLE},i$0|0x00800000)" 
 FunctionEnd

На W7x64 и W8x32 работает, а вот на WinXP нет