On mobile devices:
To include a sketch in a conversation:
- Tap the conversation you'd like to sketch in.
- Tap the Sketch
icon. - Choose the color you'd like to sketch in.
- You can use different brush sizes by tapping on the color you want to sketch with.
- Long press on the screen (Android) or tap long on a color from the color bar (iPhone/iPad) to change the background color, or to overwrite the previous sketch.
- Tap the Check
icon to send your sketch.
To undo the sketch, tap 
. To return to the conversation, tap 
.
Sketch on images:
You can sketch on images (photographs or other sketches) that are posted in a conversation.
- Tap the picture and then tap the Sketch icon.
- Shake your device to remove the original picture.
- Shake your device again to bring back the original picture.
- Tap the Check icon to send your sketch, either with or without the original picture.