Update utils.py

utils.py

@@ -538,31 +538,19 @@ def build_fig_timeline(speakers_dataFrame, currTotalTime, speaker_color_map, get
     )
     fig.update_yaxes(autorange="reversed")
 
-    # Add vertical shading for multi-voice intervals as filled scatter shapes.
-    # go.Scatter with fill="toself" supports hover; add_vrect does not.
-    MV_COLOR = "#64A377"
-    # We need the y-axis range — use a large span that covers all speaker rows
-    y_speakers = df["Resource"].unique().tolist()
-    y_min, y_max = -0.5, len(y_speakers) - 0.5
+    # Add vertical shading for multi-voice intervals.
+    # Note: add_vrect does not support hover tooltips in Plotly — this is a
+    # known Plotly limitation. Hover on these bands cannot be added without
+    # introducing extra traces that corrupt the y-axis.
     for start_s, end_s in (mv_intervals or []):
-        x0_dt = base + dt.timedelta(seconds=start_s)
-        x1_dt = base + dt.timedelta(seconds=end_s)
-        fig.add_trace(go.Scatter(
-            x=[x0_dt, x1_dt, x1_dt, x0_dt, x0_dt],
-            y=[y_min,  y_min,  y_max,  y_max,  y_min],
-            fill="toself",
-            fillcolor=f"rgba(100,163,119,0.25)",
-            line=dict(width=0),
-            mode="lines",
-            showlegend=False,
-            yaxis="y",
-            hovertemplate=(
-                f"<b>Multi Voice</b><br>"
-                f"Start: {_seconds_to_hhmmss(start_s)}<br>"
-                f"Finish: {_seconds_to_hhmmss(end_s)}"
-                "<extra></extra>"
-            ),
-        ))
+        fig.add_vrect(
+            x0=base + dt.timedelta(seconds=start_s),
+            x1=base + dt.timedelta(seconds=end_s),
+            fillcolor="#64A377",
+            opacity=0.25,
+            layer="below",
+            line_width=0,
+        )
 
     h = int(currTotalTime // 3600)
     m = int(currTotalTime %  3600 // 60)