Redo Panel

Before reading the texts in this section, try watching CG Cookie's amazing short on this Blender internal behavior: YouTube

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The redo panel is a pop up menu you can open after an operation has been confirmed or is about to be confirmed by editing any the properties.

For most operations in Blender, the redo panel is called after the operation was confirmed. You can then call this menu using the hotkey F9, allowing you to edit the properties that control the result of the executed operation hence the name redo panel.

Operation is a terminology for actions in Blender like grabbing, scaling or rotating. Not all actions in Blender have editable properties though like showing the viewport overlay, rendering, viewing the wireframe etc.

Basically, most actions/operations that can be undone using the Ctrl Z hotkey has a redo panel with their own control properties.

Figure 1

In Figure 1, the cube was scaled then the redo panel was called allowing for the operation to be re-modified accurately using the redo properties.

Figure 2

The redo panel disappears once the mouses cursor is no longer inside it. This is also internal behavior and cannot be controlled by the python script. You can bring it back using the F9 hotkey and it will reappear in the position of the mouse cursor.

Random Flow for example is heavily scripted around this behavior because this is the most dynamic worklow for an artist I can think of. For most of its operations however, the redo panel appears before any action is done and will need any modification to any of its redo properties.

Figure 3

So there are 3 redo panel behavior in Blender. First is the one you can call after the operation is confirmed, second is the redo panel that appears immediately and waits for you input and last is the what is known as the confirmation redo panel with an "OK" button.

The second and last variation both appear at the start of the operation and waits for your input but the "OK" redo panel changes to the mesh will only happen once you click the ok button - you can then show the redo panel again using the F9 hotkey.

Figure 4

When using the second variation of the redo panel, particularly with Random Flow, and the changes are not live, make sure that in preferences, under system, the global undo toggle is turned on.

Figure 5

The image above shows the redo panel of Random Panels in Random Flow with an ok button.

There is also a toggle in the Random Flow add-on preferences that will let you use this mode purposely called the Use Confirm Menu toggle to instead use the ok redo panel if you prefer this. Once the ok is clicked, the redo panel will disappear and the script will operate on the active mesh. Recall the redo panel using the F9 hotkey to make further edits. Only Random Flow has this option because of its heavy use of the second version of redo panel.