fix some ui glitch with NodeButton, start implementing working dir option

PanoPainter-OSX/main.cpp

@@ -61,6 +61,26 @@ std::mutex task_mutex;
     }
     return ret;
 }
+- (std::string)pick_dir
+{
+    NSOpenPanel *panel = [NSOpenPanel openPanel];
+    [panel setCanChooseFiles:NO];
+    [panel setCanChooseDirectories:YES];
+    [panel setAllowsMultipleSelection:NO]; // yes if more than one dir is allowed
+    
+    NSInteger clicked = [panel runModal];
+
+    std::string ret;
+    if (clicked == NSFileHandlingPanelOKButton)
+    {
+        for (NSURL *url in [panel URLs])
+        {
+            LOG("selected path: %s", [[url path] cStringUsingEncoding:NSUTF8StringEncoding]);
+            ret = [[url path] cStringUsingEncoding:NSUTF8StringEncoding];
+        }
+    }
+    return ret;
+}
 - (instancetype)initWithFrame:(NSRect)frameRect
 {
     gl_ready = false;

PanoPainter-OSX/main.h

@@ -23,4 +23,5 @@
 - (void)async_unlock;
 - (void)async_swap;
 - (std::string)pick_file:(NSArray<NSString*>*)types;
+- (std::string)pick_dir;
 @end