feat(main.py): add timeline visibility toggle functionality

main.py

@@ -57,6 +57,9 @@ class MediaGrader:
         self.segment_frames = []  # List of current frames for each segment
         self.segment_positions = []  # List of frame positions for each segment
         
+        # Timeline visibility state
+        self.timeline_visible = True
+
         # Key repeat tracking with rate limiting
         self.last_seek_time = 0
         self.current_seek_key = None
@@ -506,6 +509,12 @@ class MediaGrader:
         
         return True
 
+    def toggle_timeline(self):
+        """Toggle timeline visibility"""
+        self.timeline_visible = not self.timeline_visible
+        print(f"Timeline {'visible' if self.timeline_visible else 'hidden'}")
+        return True
+
     def setup_segment_captures(self):
         """Setup multiple video captures for segment mode"""
         if not self.is_video(self.media_files[self.current_index]):
@@ -755,7 +764,7 @@ class MediaGrader:
 
     def draw_multi_segment_timeline(self, frame):
         """Draw timeline showing all segment positions"""
-        if not self.is_video(self.media_files[self.current_index]) or not self.segment_caps:
+        if not self.is_video(self.media_files[self.current_index]) or not self.segment_caps or not self.timeline_visible:
             return
             
         height, width = frame.shape[:2]
@@ -796,8 +805,8 @@ class MediaGrader:
 
     def draw_timeline(self, frame):
         """Draw timeline at the bottom of the frame"""
-        # Only draw timeline for video files in single mode
-        if not self.is_video(self.media_files[self.current_index]) or self.multi_segment_mode:
+        # Only draw timeline for video files in single mode and when visible
+        if not self.is_video(self.media_files[self.current_index]) or self.multi_segment_mode or not self.timeline_visible:
             return
             
         height, width = frame.shape[:2]
@@ -1099,7 +1108,7 @@ class MediaGrader:
         print("  P: Previous file")
         print("  U: Undo last grading action")
         print("  L: Sample video at key points (videos only)")
-        print("  H: Undo last L jump (videos only, disabled in multi-segment)")
+        print("  H: Toggle timeline visibility")
         print("  J: Bisect backwards from current position (videos only, disabled in multi-segment)")
         print("  K: Bisect forwards toward next sample (videos only, disabled in multi-segment)")
         print("  Q/ESC: Quit")
@@ -1174,11 +1183,8 @@ class MediaGrader:
                         self.bisect_forwards()
                     else:
                         print("Navigation keys (H/J/K/L) disabled in multi-segment mode")
-                elif key == ord("h"): # Changed from "j" to "h" for undo jump
-                    if not self.multi_segment_mode:
-                        self.undo_jump()
-                    else:
-                        print("Navigation keys (H/J/K/L) disabled in multi-segment mode")
+                elif key == ord("h"): # Toggle timeline visibility
+                    self.toggle_timeline()
                 elif key == ord("g"):
                     self.toggle_multi_segment_mode()
                 elif key in [ord("1"), ord("2"), ord("3"), ord("4"), ord("5")]: