Select an item in the project and click on the icon to lock it. The selected element will always be selectable but you won't be able to move or resize it anymore. The blocked element is marked by a red border instead of gray, as shown in the image below.

The level is used to restore the rotation of an element to 0°. If you have rotated an element as in the image below.
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You can restore the rotation by clicking on the level button and the image will return to 0° as in the image below.
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Use the duplicate button to create a copy of the selected item.

Click on the element you want to duplicate and click the button.
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Use the "Bring Forward" button to move the selected element up a layer. The selected element will move up a level as you click the button until it reaches the selected level. Use this function if, for example, text is covered by an image and you want to bring the text above the image.

Use the "Bring to the background" button to move the selected element to the top layer. The selected element will gradually move down a level as you click the button until it reaches the selected level. Use this function if, for example, text covers an image and you want to bring the text below the image.

Select an item and click on the delete button to remove the text.