Material list window context menu
                                                 Create New  Material
Create New  Material
                                            Creates a new material from a template.
                                                 Import from Material Library...
Import from Material Library...
                                            Import Material from the Render Content folder, Internet connection is required to download online.
                                                 Create Physically Based material from texture files
Create Physically Based material from texture files
                                            Creates a physically based material from image files, or a PBR texture set (.zip).
Steps
- 
                                                            Select one or more image files, or a PBR texture set (.zip). Free or paid PBR texture sets can be downloaded from the Internet. 
- 
                                                            In the Texture Selection dialog, set the material name, texture assignment, texture mapping, and units. 
                                                 Paste
Paste
                                            Creates a new item based on the contents of the Clipboard.
                                                 Paste as Instance
Paste as Instance
                                            Creates a new item based on the contents of the Clipboard. The new item will be linked to the original item.
Select All
                                            Select all items in the list.
So you can change the common settings and thumbnail properties of all items.
                                                     Sort Alphabetically
Sort Alphabetically
                                                Lists the items with their names in ascending (A to Z) order.
                                                 Grid
Grid
                                            Displays the previews as a grid of thumbnails.
                                                 List
List
                                            Displays the previews as a list of thumbnails.
                                                 Tree
Tree
                                            Displays the previews as a tree showing nesting.
                                                 Show All Materials
Show All Materials
                                            Displays used and unused materials.
                                                 Show Only Used Materials
Show Only Used Materials
                                            Hides unused materials.
                                                 Show Only Unused Materials
Show Only Unused Materials
                                            Hides used materials.
                                             Horizontal Layout
Horizontal Layout
                                        Displays the previews to the left of the controls.
                                                 Show Preview Pane
Show Preview Pane
                                            Displays the selected item in a large preview section.
                                                 Float
Float
                                            Displays the list in a floating window. The panel displays the list in the Tree mode.
Thumbnails
                                             Tiny
Tiny
                                        Sets the thumbnail size to the smallest size.
                                             Small
Small
                                        Sets the thumbnail size to the smaller size.
                                             Medium
Medium
                                        Sets the thumbnail size to medium size.
                                             Large
Large
                                        Sets the thumbnail size to large size.
                                                 Show Labels
Show Labels
                                            Displays thumbnail name labels when in Grid mode.
List mode always displays labels.
                                                 Show Units
Show Units
                                            Displays the dimension of the object in the preview.
The object dimension can be changed in Preview Properties.
                                                 Auto-Update Preview
Auto-Update Preview
                                            Automatically updates all previews as settings change.
                                                 Update All Previews
Update All Previews
                                            Update previews manually when Auto-Update Preview is off.