It depends on the compiler and the operating system. You can use an os-independent compiler such as QT which as gui support for *nix, MS-Windows and MAC (others I don't know about). Or you can use os-specific libraries such as win32 api function and MFC class for MS-Windows. There are libraries for *nix too but I forget what they are.
I think that is one reason why java is supposed to be platform independent. As far as I know there really are no similar c++ compilers that produce platform independent code like that. Microsoft .NET Visual Studio is headed that way but may be several years away from achieving that goal.
>>can't find any that work
you didn't look very hard. Re-read my previous post because I gave you two. You will not find a function names "paintComponent" so no point looking for it. If you want to use c++ for gui then forget what you learning in java and learn the c/c++ way to do it.
For Each ctrl As Control In Me.Controls("pnlMainPanel").Controls
If ctrl.GetType Is GetType(System.Windows.Forms.Panel) Then
For Each subCtrl As Control In ctrl.Controls
If subCtrl.GetType Is GetType(System.Windows.Forms.TextBox) Then
If subCtrl.GetType Is ...