diff --git a/frontend/src/App.tsx b/frontend/src/App.tsx
index 9cf8787..5bdb360 100644
--- a/frontend/src/App.tsx
+++ b/frontend/src/App.tsx
@@ -26,10 +26,15 @@ export interface Frames {
   end: number;
 }
 
+export interface VideoPosition {
+  currentTime: number;
+  percent: number;
+}
+
 function App(): JSX.Element {
   const [mediaSet, setMediaSet] = useState<MediaSet | null>(null);
   const [video, _setVideo] = useState(document.createElement('video'));
-  const [position, setPosition] = useState(0);
+  const [position, setPosition] = useState({ currentTime: 0, percent: 0 });
   const [viewport, setViewport] = useState({ start: 0, end: 0 });
 
   // effects
@@ -54,10 +59,21 @@ function App(): JSX.Element {
 
   // setup player on first page load only:
   useEffect(() => {
+    if (mediaSet == null) {
+      return;
+    }
+
+    // assume mediaSet never changes once loaded
     setInterval(() => {
-      setPosition(video.currentTime);
+      if (video.currentTime == position.currentTime) {
+        return;
+      }
+      const duration = mediaSet.audioFrames / mediaSet.audioSampleRate;
+      const percent = (video.currentTime / duration) * 100;
+
+      setPosition({ currentTime: video.currentTime, percent: percent });
     }, 100);
-  }, []);
+  }, [mediaSet]);
 
   // load video when MediaSet is loaded:
   useEffect(() => {
@@ -112,12 +128,10 @@ function App(): JSX.Element {
       return;
     }
 
-    if (selection.start >= selection.end) {
-      setViewport({ start: 0, end: mediaSet.audioFrames });
-      return;
-    }
-
-    setViewport({ ...selection });
+    setViewport({
+      start: mediaSet.audioFrames * (selection.start / 100),
+      end: mediaSet.audioFrames * (selection.end / 100),
+    });
   };
 
   // render component
@@ -157,10 +171,6 @@ function App(): JSX.Element {
             offsetPixels={offsetPixels}
             height={80}
             position={position}
-            selection={viewport}
-            onSelectionStart={() => {
-              // empty
-            }}
             onSelectionChange={handleOverviewSelectionChange}
           />
 
diff --git a/frontend/src/Overview.tsx b/frontend/src/Overview.tsx
index 3490878..fcca002 100644
--- a/frontend/src/Overview.tsx
+++ b/frontend/src/Overview.tsx
@@ -1,19 +1,20 @@
 import { useState, useEffect, useRef, MouseEvent } from 'react';
 import { MediaSetServiceClientImpl, MediaSet } from './generated/media_set';
-import { Frames, newRPC } from './App';
+import { Frames, newRPC, VideoPosition } from './App';
 import { WaveformCanvas } from './WaveformCanvas';
-import { mouseEventToCanvasX } from './Helpers';
-import { secsToCanvasX } from './Helpers';
 import { from, Observable } from 'rxjs';
 import { map } from 'rxjs/operators';
 
+export interface Selection {
+  start: number;
+  end: number;
+}
+
 interface Props {
   mediaSet: MediaSet;
   height: number;
   offsetPixels: number;
-  position: number;
-  selection: Frames;
-  onSelectionStart: (x1: number) => void;
+  position: VideoPosition;
   onSelectionChange: (selection: Frames) => void;
 }
 
@@ -21,6 +22,15 @@ enum Mode {
   Normal,
   Selecting,
   Dragging,
+  ResizingStart,
+  ResizingEnd,
+}
+
+enum HoverState {
+  Normal,
+  OverSelectionStart,
+  OverSelectionEnd,
+  OverSelection,
 }
 
 const CanvasLogicalWidth = 2_000;
@@ -28,28 +38,28 @@ const CanvasLogicalHeight = 500;
 
 const emptySelection = { start: 0, end: 0 };
 
-// TODO: render position marker during playback
 export const Overview: React.FC<Props> = ({
   mediaSet,
   height,
   offsetPixels,
   position,
-  selection,
-  onSelectionStart,
   onSelectionChange,
 }: Props) => {
   const hudCanvasRef = useRef<HTMLCanvasElement>(null);
   const [peaks, setPeaks] = useState<Observable<number[]>>(from([]));
   const [mode, setMode] = useState(Mode.Normal);
-  const [newSelection, setNewSelection] = useState({ ...emptySelection });
-  const [dragStart, setDragStart] = useState(0);
+  const [hoverState, setHoverState] = useState(HoverState.Normal);
+  const [newSelection, setNewSelection] = useState({
+    ...emptySelection,
+  });
+  const [selection, setSelection] = useState({ start: 0, end: 100 });
+  const [cursor, setCursor] = useState('auto');
+
+  const moveOffsetX = useRef(0);
 
   // effects
 
   // handle global mouse up.
-  // Currently this adds and removes the global event listener every time the
-  // component is rerendered (which is often when dragging or redrawing). It
-  // works but probably better to optimize this for performance reasons.
   useEffect(() => {
     window.addEventListener('mouseup', handleMouseUp);
     return () => {
@@ -57,32 +67,53 @@ export const Overview: React.FC<Props> = ({
     };
   }, [mode, newSelection]);
 
+  // publish onSelectionChange event
+  useEffect(() => {
+    if (mediaSet == null) {
+      return;
+    }
+    const canvas = hudCanvasRef.current;
+    if (canvas == null) {
+      console.error('no hud canvas ref available');
+      return;
+    }
+    const ctx = canvas.getContext('2d');
+    if (ctx == null) {
+      console.error('no hud 2d context available');
+      return;
+    }
+
+    const width = canvas.getBoundingClientRect().width;
+    const selectionPercent = {
+      start: (selection.start / width) * 100,
+      end: (selection.end / width) * 100,
+    };
+
+    onSelectionChange(selectionPercent);
+  }, [selection]);
+
   // load peaks on mediaset change
   useEffect(() => {
     (async function () {
       if (mediaSet == null) {
         return;
       }
-
       const canvas = hudCanvasRef.current;
       if (canvas == null) {
         console.error('no hud canvas ref available');
         return;
       }
-
       const ctx = canvas.getContext('2d');
       if (ctx == null) {
         console.error('no hud 2d context available');
         return;
       }
-
       console.log('fetching audio...');
       const service = new MediaSetServiceClientImpl(newRPC());
       const audioProgressStream = service.GetAudio({
         id: mediaSet.id,
         numBins: CanvasLogicalWidth,
       });
-
       const peaks = audioProgressStream.pipe(map((progress) => progress.peaks));
       setPeaks(peaks);
     })();
@@ -90,123 +121,173 @@ export const Overview: React.FC<Props> = ({
 
   // draw the overview HUD
   useEffect(() => {
-    (async function () {
+    requestAnimationFrame(() => {
       const canvas = hudCanvasRef.current;
       if (canvas == null) {
         console.error('no hud canvas ref available');
         return;
       }
-
       const ctx = canvas.getContext('2d');
       if (ctx == null) {
         console.error('no hud 2d context available');
         return;
       }
-
       ctx.clearRect(0, 0, canvas.width, canvas.height);
 
-      // draw selection:
-      let currentSelection: Frames;
-      if (mode == Mode.Selecting || mode == Mode.Dragging) {
+      // draw selection
+
+      let currentSelection: Selection;
+      if (
+        mode == Mode.Selecting ||
+        mode == Mode.Dragging ||
+        mode == Mode.ResizingStart ||
+        mode == Mode.ResizingEnd
+      ) {
         currentSelection = newSelection;
       } else {
         currentSelection = selection;
       }
 
-      if (currentSelection.start < currentSelection.end) {
-        const x1 =
-          (currentSelection.start / mediaSet.audioFrames) * CanvasLogicalWidth;
-        const x2 =
-          (currentSelection.end / mediaSet.audioFrames) * CanvasLogicalWidth;
+      const elementWidth = canvas.getBoundingClientRect().width;
+      const start =
+        (currentSelection.start / elementWidth) * CanvasLogicalWidth;
+      const end = (currentSelection.end / elementWidth) * CanvasLogicalWidth;
 
-        ctx.beginPath();
-        ctx.strokeStyle = 'red';
-        ctx.lineWidth = 4;
-        ctx.fillStyle = 'rgba(255, 255, 255, 0.15)';
-        ctx.rect(x1, 2, x2 - x1, canvas.height - 10);
-        ctx.fill();
-        ctx.stroke();
-      }
-
-      // draw position marker:
-      const fullSelection = { start: 0, end: mediaSet.audioFrames }; // constantize?
-      const x = secsToCanvasX(
-        position,
-        mediaSet.audioSampleRate,
-        fullSelection
-      );
-      // should never happen:
-      if (x == null) {
-        return;
-      }
-
-      ctx.strokeStyle = 'red';
       ctx.beginPath();
-      ctx.moveTo(x, 0);
+      ctx.strokeStyle = 'red';
       ctx.lineWidth = 4;
-      ctx.lineTo(x, canvas.height - 4);
+      const alpha = hoverState == HoverState.OverSelection ? '0.15' : '0.13';
+      ctx.fillStyle = `rgba(255, 255, 255, ${alpha})`;
+      ctx.rect(start, 2, end - start, canvas.height - 10);
+      ctx.fill();
       ctx.stroke();
-    })();
+
+      // draw position marker
+
+      const markerX = canvas.width * (position.percent / 100);
+
+      ctx.beginPath();
+      ctx.moveTo(markerX, 0);
+      ctx.lineWidth = 4;
+      ctx.lineTo(markerX, canvas.height - 4);
+      ctx.stroke();
+    });
   });
 
-  // publish event on new selection start
-  useEffect(() => {
-    onSelectionStart(newSelection.start);
-  }, [newSelection]);
-
   // handlers
 
+  const isHoveringSelectionStart = (elementX: number): boolean => {
+    return elementX > selection.start - 10 && elementX < selection.start + 10;
+  };
+
+  const isHoveringSelectionEnd = (elementX: number): boolean => {
+    return elementX > selection.end - 10 && elementX < selection.end + 10;
+  };
+
+  const isHoveringSelection = (elementX: number): boolean => {
+    return elementX >= selection.start && elementX <= selection.end;
+  };
+
   const handleMouseDown = (evt: MouseEvent<HTMLCanvasElement>) => {
     if (mode != Mode.Normal) {
       return;
     }
 
-    const frame = Math.floor(
-      mediaSet.audioFrames *
-        (mouseEventToCanvasX(evt) / evt.currentTarget.width)
+    const elementX = Math.round(
+      evt.clientX - evt.currentTarget.getBoundingClientRect().x
     );
 
-    if (frame >= selection.start && frame < selection.end) {
+    if (isHoveringSelectionStart(elementX)) {
+      setMode(Mode.ResizingStart);
+      moveOffsetX.current = elementX;
+      return;
+    } else if (isHoveringSelectionEnd(elementX)) {
+      setMode(Mode.ResizingEnd);
+      moveOffsetX.current = elementX;
+      return;
+    } else if (isHoveringSelection(elementX)) {
       setMode(Mode.Dragging);
-      setDragStart(frame);
+      setCursor('pointer');
+      moveOffsetX.current = elementX;
       return;
     }
 
     setMode(Mode.Selecting);
-    setNewSelection({ start: frame, end: frame });
+    setCursor('col-resize');
+    moveOffsetX.current = elementX;
+    setNewSelection({ start: elementX, end: elementX });
   };
 
   const handleMouseMove = (evt: MouseEvent<HTMLCanvasElement>) => {
-    if (mode == Mode.Normal) {
-      return;
-    }
-
-    const frame = Math.floor(
-      mediaSet.audioFrames *
-        (mouseEventToCanvasX(evt) / evt.currentTarget.width)
+    const x = Math.round(
+      evt.clientX - evt.currentTarget.getBoundingClientRect().x
     );
 
-    if (mode == Mode.Dragging) {
-      const diff = frame - dragStart;
-      const frameCount = selection.end - selection.start;
-      let start = Math.max(0, selection.start + diff);
-      let end = start + frameCount;
-      if (end > mediaSet.audioFrames) {
-        end = mediaSet.audioFrames;
-        start = end - frameCount;
+    switch (mode) {
+      case Mode.Normal: {
+        if (isHoveringSelectionStart(x)) {
+          setHoverState(HoverState.OverSelectionStart);
+          setCursor('col-resize');
+        } else if (isHoveringSelectionEnd(x)) {
+          setHoverState(HoverState.OverSelectionEnd);
+          setCursor('col-resize');
+        } else if (isHoveringSelection(x)) {
+          setHoverState(HoverState.OverSelection);
+          setCursor('pointer');
+        } else {
+          setCursor('auto');
+        }
+        break;
       }
-      setNewSelection({
-        start: start,
-        end: end,
-      });
-      return;
-    }
+      case Mode.ResizingStart: {
+        const diff = x - moveOffsetX.current;
+        const start = selection.start + diff;
 
-    if (frame == newSelection.end) {
-      return;
-    }
+        if (start > selection.end) {
+          setNewSelection({ start: selection.end, end: start });
+          break;
+        }
 
-    setNewSelection({ ...newSelection, end: frame });
+        setNewSelection({ ...newSelection, start: start });
+        break;
+      }
+      case Mode.ResizingEnd: {
+        const diff = x - moveOffsetX.current;
+        const start = selection.end + diff;
+
+        if (start < selection.start) {
+          setNewSelection({ start: Math.max(0, start), end: selection.start });
+          break;
+        }
+
+        setNewSelection({ ...newSelection, end: start });
+        break;
+      }
+      case Mode.Dragging: {
+        const diff = x - moveOffsetX.current;
+        const width = selection.end - selection.start;
+        let start = Math.max(0, selection.start + diff);
+        let end = start + width;
+        if (end > evt.currentTarget.getBoundingClientRect().width) {
+          end = evt.currentTarget.getBoundingClientRect().width;
+          start = end - width;
+        }
+
+        setNewSelection({ start: start, end: end });
+        break;
+      }
+      case Mode.Selecting: {
+        if (x < moveOffsetX.current) {
+          setNewSelection({
+            start: x,
+            end: moveOffsetX.current,
+          });
+        } else {
+          setNewSelection({ start: moveOffsetX.current, end: x });
+        }
+        break;
+      }
+    }
   };
 
   const handleMouseUp = () => {
@@ -215,7 +296,22 @@ export const Overview: React.FC<Props> = ({
     }
 
     setMode(Mode.Normal);
-    onSelectionChange({ ...newSelection });
+    setCursor('auto');
+
+    if (newSelection.start == newSelection.end) {
+      setSelection({ start: newSelection.start, end: newSelection.end + 5 });
+      return;
+    }
+
+    if (newSelection.start == newSelection.end) {
+      setSelection({ ...emptySelection });
+      return;
+    }
+    setSelection({ ...newSelection });
+  };
+
+  const handleMouseLeave = (_evt: MouseEvent<HTMLCanvasElement>) => {
+    setHoverState(HoverState.Normal);
   };
 
   // render component
@@ -233,6 +329,7 @@ export const Overview: React.FC<Props> = ({
     height: '100%',
     display: 'block',
     zIndex: 2,
+    cursor: cursor,
   } as React.CSSProperties;
 
   return (
@@ -255,6 +352,7 @@ export const Overview: React.FC<Props> = ({
           style={hudCanvasStyles}
           onMouseDown={handleMouseDown}
           onMouseMove={handleMouseMove}
+          onMouseLeave={handleMouseLeave}
         ></canvas>
       </div>
     </>
diff --git a/frontend/src/VideoPreview.tsx b/frontend/src/VideoPreview.tsx
index 8abd30f..a2dee50 100644
--- a/frontend/src/VideoPreview.tsx
+++ b/frontend/src/VideoPreview.tsx
@@ -1,10 +1,10 @@
 import { MediaSet, MediaSetServiceClientImpl } from './generated/media_set';
-import { newRPC } from './App';
+import { newRPC, VideoPosition } from './App';
 import { useEffect, useRef } from 'react';
 
 interface Props {
   mediaSet: MediaSet;
-  position: number;
+  position: VideoPosition;
   duration: number;
   height: number;
   video: HTMLVideoElement;
@@ -46,7 +46,7 @@ export const VideoPreview: React.FC<Props> = ({
         // trying to render the video. The most important use case is before a
         // click event has happened, when autoplay restrictions will prevent
         // the video being rendered to canvas.
-        if (position == 0) {
+        if (position.currentTime == 0) {
           const service = new MediaSetServiceClientImpl(newRPC());
           const thumbnail = await service.GetVideoThumbnail({
             id: mediaSet.id,
@@ -65,14 +65,14 @@ export const VideoPreview: React.FC<Props> = ({
 
         // otherwise, render the video, which (should) work now.
         const durSecs = duration / 1000;
-        const ratio = position / durSecs;
+        const ratio = position.currentTime / durSecs;
         const x = (canvas.width - 177) * ratio;
         ctx.clearRect(0, 0, x, canvas.height);
         ctx.clearRect(x + 177, 0, canvas.width - 177 - x, canvas.height);
         ctx.drawImage(video, x, 0, 177, 100);
       })();
     });
-  }, [mediaSet, position]);
+  }, [mediaSet, position.currentTime]);
 
   // render component
 
diff --git a/frontend/src/Waveform.tsx b/frontend/src/Waveform.tsx
index ed991ac..be2c3ad 100644
--- a/frontend/src/Waveform.tsx
+++ b/frontend/src/Waveform.tsx
@@ -1,5 +1,5 @@
 import { useEffect, useState, useRef } from 'react';
-import { Frames, newRPC } from './App';
+import { Frames, VideoPosition, newRPC } from './App';
 import { MediaSetServiceClientImpl, MediaSet } from './generated/media_set';
 import { WaveformCanvas } from './WaveformCanvas';
 import { secsToCanvasX } from './Helpers';
@@ -8,7 +8,7 @@ import { bufferCount } from 'rxjs/operators';
 
 interface Props {
   mediaSet: MediaSet;
-  position: number;
+  position: VideoPosition;
   viewport: Frames;
   offsetPixels: number;
 }
@@ -76,7 +76,7 @@ export const Waveform: React.FC<Props> = ({
       return;
     }
 
-    const x = secsToCanvasX(position, mediaSet.audioSampleRate, viewport);
+    const x = secsToCanvasX(position.currentTime, mediaSet.audioSampleRate, viewport);
     if (x == null) {
       return;
     }