Setup programs for Windows
Alberto, why did you chose NSIS to build setup programs? I don’t like it because its scripting language seems a mix between assembly and shell scripting and it doesn’t even have flow control statements, you have to use Goto!
Moreover you have to do manually everthing, for instance to copy a file that later can be uninstalled you need this code:
; Copy the file File "example.exe" ; Create shortcuts. CeateDirectory "$SMPROGRAMS\\Example" CreateShortCut "$SMPROGRAMS\\Example\\Uninstall.lnk" "$INSTDIR\\uninstall.exe" "" "$INSTDIR\\uninstall.exe" 0 CreateShortCut "$SMPROGRAMS\\Example\\Example.lnk" "$INSTDIR\\example.exe" "" "$INSTDIR\\example.exe" 0 ; Copy the uninstaller. WriteUninstaller "uninstall.exe" ; Write the uninstall keys for Windows. WriteRegStr HKLM "Software\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\Example" "DisplayName" "NSIS Example" WriteRegStr HKLM "Software\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\Example" "UninstallString" '"$INSTDIR\\uninstall.exe"' WriteRegDWORD HKLM "Software\\Microsoft\\Windows\\CurrentVersion\Uninstall\\Example" "NoModify" 1 WriteRegDWORD HKLM "Software\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\Example" "NoRepair" 1 WriteUninstaller "uninstall.exe"
And then you have to uninstall everything manually:
; Delete registry keys. DeleteRegKey HKLM "Software\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\Example" ; Remove files and uninstaller. Delete $INSTDIR\\example.exe Delete $INSTDIR\\uninstall.exe ; Remove shortcuts. Delete "$SMPROGRAMS\\Example\\Uninstall.lnk" Delete "$SMPROGRAMS\\Example\\Example.lnk" RMDir "$SMPROGRAMS\\Example" ; Remove the program directory. RMDir "$INSTDIR"
I prefer Inno Setup, the nice thing is that for common tasks (copying files, creating shortcuts, adding registry keys, etc.) you only have to write a simple ini-like file, but if you need something more powerful you can use Pascal scripting.
The previous example in Inno Setup would be:
[Files]
Source: "example.exe"; DestDir: "{app}"
[Icons]
Name: "{group}\\Example"; Filename: "{app}\\example.exe"
Name: "{group}\\Uninstall"; Filename: "{uninstallexe}"
Please, use Inno Setup! 
NSIS is open source, that’s probably the answer to the “Why…” question.. ;)