Use nativefiledialog instead of tinyfiledialog

tinyfiledialog is a bit annoying because it relies on external tools
that might not be installed on the running machine.

An other issue is that current version of zenity used on linux doesn't
support setting the default save path.

Here I replace with tinyfiledialog that seems to be more reliable.

For the linux AppImage I use the dbus backend so that it should use the
system default style.

Makefile

@@ -31,8 +31,9 @@ format: .FORCE
 
 
 # Generate an AppImage.  Used by github CI.
-appimage:
-	scons mode=release
+appimage: .FORCE
+	scons mode=release nfd_backend=portal
+	rm -rf AppDir
 	mkdir AppDir
 	DESTDIR=AppDir PREFIX=/usr make install
 	curl https://github.com/linuxdeploy/linuxdeploy/releases/download/1-alpha-20231206-1/linuxdeploy-x86_64.AppImage \

SConstruct

@@ -31,6 +31,13 @@ vars.AddVariables(
 
 target_os = str(Platform())
 
+if target_os == 'posix':
+    vars.AddVariables(
+        EnumVariable('nfd_backend', 'Native file dialog backend', default='gtk',
+                     allowed_values=('gtk', 'portal')),
+    )
+
+
 env = Environment(variables=vars, ENV=os.environ)
 conf = env.Configure()
 
@@ -94,32 +101,47 @@ if target_os == 'posix':
     # Note: add '--static' to link with all the libs needed by glfw3.
     env.ParseConfig('pkg-config --libs glfw3')
 
+    # Pick the proper native file dialog backend.
+    if env['nfd_backend'] == 'portal':
+        env.ParseConfig('pkg-config --cflags --libs dbus-1')
+        sources.append('ext_src/nfd/nfd_portal.cpp')
+
+    if env['nfd_backend'] == 'gtk':
+        env.ParseConfig('pkg-config --cflags --libs gtk+-3.0')
+        sources.append('ext_src/nfd/nfd_gtk.cpp')
+
+
 # Windows compilation support.
 if target_os == 'msys':
     env.Append(CXXFLAGS=['-Wno-attributes', '-Wno-unused-variable',
                          '-Wno-unused-function'])
     env.Append(CCFLAGS=['-Wno-error=address']) # To remove if possible.
     env.Append(LIBS=['glfw3', 'opengl32', 'z', 'tre', 'gdi32', 'Comdlg32',
-                     'ole32'],
+                     'ole32', 'uuid', 'shell32'],
                LINKFLAGS='--static')
     sources += glob.glob('ext_src/glew/glew.c')
+    sources.append('ext_src/nfd/nfd_win.cpp')
     env.Append(CPPPATH=['ext_src/glew'])
     env.Append(CPPDEFINES=['GLEW_STATIC', 'FREE_WINDOWS'])
 
 # OSX Compilation support.
 if target_os == 'darwin':
     sources += glob.glob('src/*.m')
-    env.Append(FRAMEWORKS=['OpenGL', 'Cocoa'])
+    sources.append('ext_src/nfd/nfd_cocoa.m')
+    env.Append(FRAMEWORKS=[
+        'OpenGL', 'Cocoa', 'AppKit', 'UniformTypeIdentifiers'])
     env.Append(LIBS=['m', 'objc'])
     # Fix warning in noc_file_dialog (the code should be fixed instead).
     env.Append(CCFLAGS=['-Wno-deprecated-declarations'])
     env.ParseConfig('pkg-config --cflags --libs glfw3')
     env['sound'] = False
 
+
 # Add external libs.
 env.Append(CPPPATH=['ext_src'])
 env.Append(CPPPATH=['ext_src/uthash'])
 env.Append(CPPPATH=['ext_src/stb'])
+env.Append(CPPPATH=['ext_src/nfd'])
 env.Append(CPPPATH=['ext_src/noc'])
 env.Append(CPPPATH=['ext_src/xxhash'])
 env.Append(CPPPATH=['ext_src/meshoptimizer'])