In Blender, we want to make it easier to set values for multiple objects, bones, strips, keys and other items at once.
Currently you can do this in limited circumstances, but you have to right-click on a value after you've changed it and pick Copy to Selected from the menu or hold Alt while editing values. This not only slow, but also very hidden, and the Alt-key conflicts with Emulate 3 Button Mouse. Lastly, it isn't clear at all to users which values work for multi-editing, and which values don't.
Here's how we would like to solve it:
Selection vs Active
The concept of active in Blender means that we only show properties and only affect the active object or item. However, if we want to better support multi-item editing, we must start by making it so the Properties reflects the selection rather than the active item, of which there can only be one. Going forward, by default the Properties will be set to reflect the selection instead. This could be controlled in the Properties like so:
(The search box is added here to reflect how the Properties will be updated when that item is also added, but is a separate feature)
If set to Active, the Properties will continue to function as it does today, only showing properties for the active item.
When there are multiple selected items
When the user has selected multiple items, a few things change:
Instead of showing the name of the object at the top, Blender tells the user how many items are selected:
In the list of tabs, only properties sections are shown that are common among the selected items. For example, if you select a text and a mesh object, we don't show Modifier, Mesh or Curve Properties, since these properties only exist on a subset of the selected objects:
This rule also goes for individual panels. Here, both a Sun and Spot light are selected, and we only see properties that are shared between them. A note at the bottom clarifies that you are only seeing the shared subset:
When values differ
When multiple items are selected, Blender will compare values to check if they are the same, or if they are different. If they differ, we change the way properties are displayed, like so:
Manipulating values across multiple items
For simply setting a value to be the same. you would simply type a new value, hit Return, and that value is then propagated to the selection.
For manipulating numbers and sliders relatively, you can just drag on them (like Alt-dragging today), or type the character '=', so the user can type '= -3' to subtract 3 from the value on all selected items.