I've got this question also on StackOverflow:
I created an nsdialog from the tutorials.
I have a section that is correctly displaying my custom dialog at the right time, but doesn't allow me to do any next/back/cancel or close action.
What magick must be invoked to activate the buttons?

Here's the section:
Var Dialog
Var Label
Var MyTextbox
#Page custom configLocationDialog configLocationDialogLeave
#Page custom doConfiguration
Section configLocationDialog
nsDialogs::Create 1018
Pop $Dialog
${If} $Dialog == error
Abort
${EndIf}
GetFunctionAddress $0 "configLocationDialogLeave"
nsDialogs::OnBack $Dialog $0
#nsDialogs::OnNext $Dialog
${NSD_CreateLabel} 0 0 100% 12u "Hello, welcome to nsDialogs!"
Pop $Label
${NSD_CreateText} 10% 20u 80% 12u "Hello World"
Pop $MyTextbox
nsDialogs::Show
SectionEnd