Add support for right-aligned checkboxes to wxOSX

Honour wxALIGN_RIGHT style.

Closes #17380.

docs/changes.txt

@@ -234,3 +234,4 @@ wxOSX/Cocoa:
 - Don't generate wxEVT_TEXT_ENTER for controls without wxTE_PROCESS_ENTER.
 - Implement wxToolTip::SetDelay() (David Vanderson).
 - Correct positioning of popup menus relative to mouse pointer (John Roberts).
+- Add support for right-aligned checkboxes (John Roberts).

interface/wx/checkbox.h

@@ -56,8 +56,7 @@ enum wxCheckBoxState
            It can only be done from code. Using this flags allows the user to
            set the checkbox to the third state by clicking.
     @style{wxALIGN_RIGHT}
-           Makes the text appear on the left of the checkbox. Not implemented
-           in wxOSX.
+           Makes the text appear on the left of the checkbox.
     @endStyleTable
 
     @beginEventEmissionTable{wxCommandEvent}

src/osx/cocoa/checkbox.mm

@@ -28,6 +28,8 @@ wxWidgetImplType* wxWidgetImpl::CreateCheckBox( wxWindowMac* wxpeer,
     wxNSButton* v = [[wxNSButton alloc] initWithFrame:r];
 
     [v setButtonType:NSSwitchButton];
+    if (style & wxALIGN_RIGHT)
+        [v setImagePosition:NSImageRight];
     if (style & wxCHK_3STATE)
         [v setAllowsMixedState:YES];