conditional os in UI xml, add system dialog file open on osx, check api format or error message when opening a document, per-char text wrap on NodeText, additional info on create doc dialog like working path

src/font.h

@@ -40,6 +40,7 @@ class TextMesh
 public:
     GLuint font_array = 0;
     int font_array_count = 0;
+    int max_width = 0;
     GLuint font_buffers[2] = {0, 0};
     kFont font_id;
     glm::vec2 bb = { 0, 0 };