Error compiling Gtkmm4 AlertDialog example

[WillyAguilera1977]

Compiling the AlertDialog example from the Programming with Gtkmm 4 book returns 15 errors.

1. Error (active) E0040 expected identifier ThirdCPPGTK4 C:\Programming\CPP\GTK4_Gvsbuild\include\gtkmm-4.0\gtkmm\stringsorter.h 65
2. Error C2143 syntax error: missing '}' before 'constant' ThirdCPPGTK4 C:\Programming\CPP\GTK4_Gvsbuild\include\gtkmm-4.0\gtkmm\stringsorter.h 65
3. Error C2059 syntax error: 'constant' ThirdCPPGTK4 C:\Programming\CPP\GTK4_Gvsbuild\include\gtkmm-4.0\gtkmm\stringsorter.h 65
   The list of errors continues in the same file 'stringsorter.h'
   I'm using Visual Studio 2019 to compile the program.
   I'm using GTK4_Gvsbuild_2025.9.0_x64.zip