Fix: Correct heading style detection

Fixes #625

Just count leading and trailing hash tags and compare the amount in
order to decide for style. This ignores SETEXT headings and fixes an
edge case caused by new syntax definition.

plugins/headings/style.py

@@ -76,19 +76,16 @@ def auto_detect_heading_style(self):
             view.settings().set("mde.auto_match_heading_hashes", False)
             return
 
-        num_leading = 0
-        num_trailing = 0
-
-        for h1, h2 in zip(
-            view.find_by_selector("markup.heading")[:10],
-            view.find_by_selector("markup.heading - punctuation.definition.heading")[:10],
-        ):
-            num_leading += 1
-            if h1.end() > h2.end():
-                num_trailing += 1
-
+        num_leading = len(
+            view.find_by_selector("markup.heading punctuation.definition.heading.begin")
+        )
         if num_leading:
+            num_trailing = len(
+                view.find_by_selector("markup.heading punctuation.definition.heading.end")
+            )
             view.settings().set("mde.match_heading_hashes", num_trailing / num_leading > 0.5)
+        else:
+            view.settings().erase("mde.match_heading_hashes")
 
         if view.settings().get("mde.auto_match_heading_hashes", False):
             view.run_command("mde_match_heading_hashes")