macOS: Add "Show hidden files" button to native file chooser

src/Fl_Native_File_Chooser_MAC.mm

@@ -551,40 +551,77 @@ static char *prepareMacFilter(int count, const char *filter, char **patterns) {
 }
 @end
 
+
+@interface FLHiddenFilesAction : NSObject
+{
+@public
+  NSSavePanel *panel;
+  NSButton *button;
+}
+- (void)action;
+@end
+@implementation FLHiddenFilesAction
+- (void)action {
+  [panel setShowsHiddenFiles:[button intValue]];
+}
+@end
+
+
 static NSPopUpButton *createPopupAccessory(NSSavePanel *panel, const char *filter, const char *title, int rank)
 {
   NSPopUpButton *popup;
-  NSRect rectview = NSMakeRect(5, 5, 350, 30 );
+  NSRect rectview = NSMakeRect(5, 5, 350, filter ? 60 : 30);
   NSView *view = [[[NSView alloc] initWithFrame:rectview] autorelease];
   NSRect rectbox = NSMakeRect(0, 3, 140, 20 );
-  NSBox *box = [[[NSBox alloc] initWithFrame:rectbox] autorelease];
-  NSRect rectpop = NSMakeRect(105, 0, 246, 30 );
-  popup = [[[NSPopUpButton alloc ] initWithFrame:rectpop pullsDown:NO] autorelease];
-  [view addSubview:box];
-  [view addSubview:popup];
-  [box setBorderType:NSNoBorder];
-  NSString *nstitle = [[NSString alloc] initWithUTF8String:title];
-  [box setTitle:nstitle];
-  [nstitle release];
-  NSFont *font = [NSFont controlContentFontOfSize:NSRegularControlSize];
-  [box setTitleFont:font];
-  [box sizeToFit];
-  // horizontally move box to fit the locale-dependent width of its title
-  NSRect r=[box frame];
-  NSPoint o = r.origin;
-  o.x = rectpop.origin.x - r.size.width + 15;
-  [box setFrameOrigin:o];
-  CFStringRef tab = CFSTR("\n");
-  CFStringRef tmp_cfs;
-  tmp_cfs = CFStringCreateWithCString(NULL, filter, kCFStringEncodingUTF8);
-  CFArrayRef array = CFStringCreateArrayBySeparatingStrings(NULL, tmp_cfs, tab);
-  CFRelease(tmp_cfs);
-  CFRelease(tab);
-  [popup addItemsWithTitles:(NSArray*)array];
-  NSMenuItem *item = [popup itemWithTitle:@""];
-  if (item) [popup removeItemWithTitle:@""];
-  CFRelease(array);
-  [popup selectItemAtIndex:rank];
+  // the "Show hidden files" button
+  NSRect hidden_files_rect = {{150, (filter ? 35 : 0)}, {80, 30}};
+  NSButton *hidden_files = [[[NSButton alloc] initWithFrame:hidden_files_rect] autorelease];
+  [hidden_files setButtonType:
+#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_12
+      NSButtonTypeSwitch
+#else
+      NSSwitchButton
+#endif
+  ];
+  [hidden_files setTitle:[NSString stringWithUTF8String:Fl_File_Chooser::hidden_label]];
+  [hidden_files sizeToFit];
+  [hidden_files setIntValue:0];
+  [view addSubview:hidden_files];
+  static FLHiddenFilesAction *target = [[FLHiddenFilesAction alloc] init]; // never released
+  target->panel = panel;
+  target->button = hidden_files;
+  [hidden_files setAction:@selector(action)];
+  [hidden_files setTarget:target];
+  if (filter) {
+    NSBox *box = [[[NSBox alloc] initWithFrame:rectbox] autorelease];
+    NSRect rectpop = NSMakeRect(105, 0, 246, 30 );
+    popup = [[[NSPopUpButton alloc ] initWithFrame:rectpop pullsDown:NO] autorelease];
+    [view addSubview:box];
+    [view addSubview:popup];
+    [box setBorderType:NSNoBorder];
+    NSString *nstitle = [[NSString alloc] initWithUTF8String:title];
+    [box setTitle:nstitle];
+    [nstitle release];
+    NSFont *font = [NSFont controlContentFontOfSize:NSRegularControlSize];
+    [box setTitleFont:font];
+    [box sizeToFit];
+    // horizontally move box to fit the locale-dependent width of its title
+    NSRect r=[box frame];
+    NSPoint o = r.origin;
+    o.x = rectpop.origin.x - r.size.width + 15;
+    [box setFrameOrigin:o];
+    CFStringRef tab = CFSTR("\n");
+    CFStringRef tmp_cfs;
+    tmp_cfs = CFStringCreateWithCString(NULL, filter, kCFStringEncodingUTF8);
+    CFArrayRef array = CFStringCreateArrayBySeparatingStrings(NULL, tmp_cfs, tab);
+    CFRelease(tmp_cfs);
+    CFRelease(tab);
+    [popup addItemsWithTitles:(NSArray*)array];
+    NSMenuItem *item = [popup itemWithTitle:@""];
+    if (item) [popup removeItemWithTitle:@""];
+    CFRelease(array);
+    [popup selectItemAtIndex:rank];
+  }
   [panel setAccessoryView:view];
   return popup;
 }
@@ -710,7 +747,7 @@ int Fl_Quartz_Native_File_Chooser_Driver::post() {
       FLopenDelegate *openDelegate = [[[FLopenDelegate alloc] init] autorelease];
       [openDelegate setPopup:popup filter_pattern:_filt_patt];
       [_panel setDelegate:openDelegate];
-    }
+    } else createPopupAccessory(_panel, NULL, Fl_File_Chooser::show_label, 0);
   }
   else {
     FLsaveDelegate *saveDelegate = [[[FLsaveDelegate alloc] init] autorelease];
@@ -738,7 +775,7 @@ int Fl_Quartz_Native_File_Chooser_Driver::post() {
       }
       [_panel setCanSelectHiddenExtension:YES];
       [_panel setExtensionHidden:NO];
-    }
+    } else createPopupAccessory(_panel, NULL, Fl_File_Chooser::show_label, 0);
   }
   int retval = runmodal();
   if (_filt_total) {