As someone said above, command + tab works as the alt + tab equivalent for mac Also, as a mac owner myself, I DO NOT recommend putting D3 into fullscreen windowed as it really hits your gpu/cpu hard (in my experience). Unless you're on a desktop mac, then you should be ok. Level 1 1percentjuice.

Use the Screenshot toolbar

To view the Screenshot toolbar, press these three keys together: Shift, Command, and 5. You will see onscreen controls for recording the entire screen, recording a selected portion of the screen, or capturing a still image of your screen:

Record the entire screen

1. Click in the onscreen controls. Your pointer changes to a camera .
2. Click any screen to start recording that screen, or click Record in the onscreen controls.
3. To stop recording, click in the menu bar. Or press Command-Control-Esc (Escape).
4. Use the thumbnail to trim, share, save, or take other actions.

Record a selected portion of the screen

1. Click in the onscreen controls.
2. Drag to select an area of the screen to record. To move the entire selection, drag from within the selection.
   
3. To start recording, click Record in the onscreen controls.
4. To stop recording, click in the menu bar. Or press Command-Control-Esc (Escape).
5. Use the thumbnail to trim, share, save, or take other actions.

Trim, share, and save

After you stop recording, a thumbnail of the video appears briefly in the lower-right corner of your screen.

• Take no action or swipe the thumbnail to the right and the recording is automatically saved.
• Click the thumbnail to open the recording. You can then click to trim the recording, or click to share it.
• Drag the thumbnail to move the recording to another location, such as to a document, an email, a Finder window, or the Trash.
• Control-click the thumbnail for more options. For example, you can change the save location, open the recording in an app, or delete the recording without saving it.

Change the settings

Click Options in the onscreen controls to change these settings:

• Save to: Choose where your recordings are automatically saved, such as Desktop, Documents, or Clipboard.
• Timer: Choose when to begin recording: immediately, 5 seconds, or 10 seconds after you click to record.
• Microphone: To record your voice or other audio along with your recording, choose a microphone.
• Show Floating Thumbnail: Choose whether to show the thumbnail.
• Remember Last Selection: Choose whether to default to the selections you made the last time you used this tool.
• Show Mouse Clicks: Choose whether to show a black circle around your pointer when you click in the recording.

Use QuickTime Player

1. Open QuickTime Player from your Applications folder, then choose File > New Screen Recording from the menu bar. You will then see either the onscreen controls described above or the Screen Recording window described below.
2. Before starting your recording, you can click the arrow next to to change the recording settings:
   
   • To record your voice or other audio with the screen recording, choose a microphone. To monitor that audio during recording, adjust the volume slider. If you get audio feedback, lower the volume or use headphones with a microphone.
     
   • To show a black circle around your pointer when you click, choose Show Mouse Clicks in Recording.
     
3. To start recording, click and then take one of these actions:
   • Click anywhere on the screen to begin recording the entire screen.
   • Or drag to select an area to record, then click Start Recording within that area.
4. To stop recording, click in the menu bar, or press Command-Control-Esc (Escape).
5. After you stop recording, QuickTime Player automatically opens the recording. You can now play, edit, or share the recording.

Learn more

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• The Screenshot toolbar is available in macOS Mojave or later.
• When saving your recording automatically, your Mac uses the name ”Screen Recording date at time.mov”.
• To cancel making a recording, press the Esc key before clicking to record.
• You can open screen recordings with QuickTime Player, iMovie, and other apps that can edit or view videos.
• Some apps might not let you record their windows.
• Learn how to record the screen on your iPhone, iPad, or iPod touch.

Use the Screenshot toolbar

To view the Screenshot toolbar, press these three keys together: Shift, Command, and 5. You will see onscreen controls for recording the entire screen, recording a selected portion of the screen, or capturing a still image of your screen:

Record the entire screen

1. Click in the onscreen controls. Your pointer changes to a camera .
2. Click any screen to start recording that screen, or click Record in the onscreen controls.
3. To stop recording, click in the menu bar. Or press Command-Control-Esc (Escape).
4. Use the thumbnail to trim, share, save, or take other actions.

Record a selected portion of the screen

1. Click in the onscreen controls.
2. Drag to select an area of the screen to record. To move the entire selection, drag from within the selection.
   
3. To start recording, click Record in the onscreen controls.
4. To stop recording, click in the menu bar. Or press Command-Control-Esc (Escape).
5. Use the thumbnail to trim, share, save, or take other actions.

Trim, share, and save

After you stop recording, a thumbnail of the video appears briefly in the lower-right corner of your screen.

Macos - How To Make A Game Full Screen On My External Monitor ...

• Take no action or swipe the thumbnail to the right and the recording is automatically saved.
• Click the thumbnail to open the recording. You can then click to trim the recording, or click to share it.
• Drag the thumbnail to move the recording to another location, such as to a document, an email, a Finder window, or the Trash.
• Control-click the thumbnail for more options. For example, you can change the save location, open the recording in an app, or delete the recording without saving it.

Change the settings

Click Options in the onscreen controls to change these settings:

• Save to: Choose where your recordings are automatically saved, such as Desktop, Documents, or Clipboard.
• Timer: Choose when to begin recording: immediately, 5 seconds, or 10 seconds after you click to record.
• Microphone: To record your voice or other audio along with your recording, choose a microphone.
• Show Floating Thumbnail: Choose whether to show the thumbnail.
• Remember Last Selection: Choose whether to default to the selections you made the last time you used this tool.
• Show Mouse Clicks: Choose whether to show a black circle around your pointer when you click in the recording.

Use QuickTime Player

1. Open QuickTime Player from your Applications folder, then choose File > New Screen Recording from the menu bar. You will then see either the onscreen controls described above or the Screen Recording window described below.
2. Before starting your recording, you can click the arrow next to to change the recording settings:
   
   • To record your voice or other audio with the screen recording, choose a microphone. To monitor that audio during recording, adjust the volume slider. If you get audio feedback, lower the volume or use headphones with a microphone.
     
   • To show a black circle around your pointer when you click, choose Show Mouse Clicks in Recording.
     
3. To start recording, click and then take one of these actions:
   • Click anywhere on the screen to begin recording the entire screen.
   • Or drag to select an area to record, then click Start Recording within that area.
4. To stop recording, click in the menu bar, or press Command-Control-Esc (Escape).
5. After you stop recording, QuickTime Player automatically opens the recording. You can now play, edit, or share the recording.

Learn more

• The Screenshot toolbar is available in macOS Mojave or later.
• When saving your recording automatically, your Mac uses the name ”Screen Recording date at time.mov”.
• To cancel making a recording, press the Esc key before clicking to record.
• You can open screen recordings with QuickTime Player, iMovie, and other apps that can edit or view videos.
• Some apps might not let you record their windows.
• Learn how to record the screen on your iPhone, iPad, or iPod touch.