▪Basically, we use the edit tool , transform tool , and copy/paste Properties tool to do all the editing.
 

▪Transform Items

You could move the item, and set up its size in the attribute editor,

beside that, you use the transform tool to transform buttons' size & position, the hotkey for this tool is "T".

Select picker items, enter this tool to transform them, press Enter/Return key to confirm the transformation, and Escape key to cancel the transformation.

Use "ALT + Enter/Return" to apply the mirrored transformation to the mirrored items.

From v2, by default, the transform tool will also transform all the children if you are transforming a group or panel.

This option can be switched on/off in its context menu, keep in mind that the option is not part of user preference so it won't survive different MG-Picker Studio sessions.

▪Build your own style library:

Check it out here.

▪Transform Bezier / Polygon Shape:

You could rotate/flip bezier curves and polygon shapes, just go to Edit Menu / Transform Bezier/Polygon Item..

▪Duplicate Items

Select a picker item, press "CTRL + D" to duplicate them, and position the duplications below them.

"CTRL + SHIFT + D" to duplicate and position the duplications to the right side of them.

Holding the ALT key while doing this, will position the duplications to the opposite side, say the left or top side of the original items.
 

▪Copy / Paste Items

CTRL + C / CTRL + V also works for the select items.

You could copy items and paste them into other picker files.

When copying items, if picker panels are selected, only panels will be copied, other types of items are skipped.
 

▪Copy / Paste Item Properties

Switch to copy/paste property tool , to transfer the properties between picker items. use hotkey "I" for that.

To copy the properties, right-click on the item, and select a copy mode.

LMB clicks on the item to paste the properties.
 

▪Align / Evenly Distribute Items

Use the align/distribute buttons in the UI, or the corresponding menus in the Edit menu, to align / evenly distribute selected picker items.

Starting from v2.3, you got extra alignToLastSelection button , if you turn it on, the alignment is done with the reference to the last selected item.

Otherwise, for aligning H/V center, the average center is used, for aligning to left/right/top/bottom, the most left/right/top/bottom is used.
 

▪Scale Items to Proper Sizes

Select some picker items, and press "CTRL + R" to rescale them to their proper sizes. The same feature is available in the Edit menu.
 

▪Adjust Items Fill Color

You could adjust the color of the item in the attribute editor.

But if you wanna tweak the color in photoshop way:

Select some picker items, and press "CTRL + U" to bring up the "Adjust Button Color" dialog.

It is very similar to photoshop's "Hue & Saturation" dialog.
 

▪Set Properties To Mirrored Items

Use the ALT key.

Say setting the label margin, input the label margin, and press ALT+Enter, the mirrored item will be applied to the mirrored label margin.

Say you are transforming items using the transform tool, user ALT+Enter, to apply the mirrored transformation to the mirrored items.
 

▪Parent / Unparent Items

All types of picker items, including the picker group/panel itself, could be parented into a picker group/panel.

Simply use P and Shift+P to parent or unparent items.

By default when you create a picker item upon a picker panel, the item will automatically be the child item of the panel below.

To parent items to a panel, select and move the items over the panel, make sure you are in  tool, right-click and select "Parent To Panel Below".

In the same way, if you wanna unparent items from a panel, select them, right-click and select "Unparent From Parent Panel";
 

▪Auto-Label Items

Select some picker items, and press "CTRL + L" to auto-label them.

An alternative way, press the < button beside the label field in the attribute editor.

▪Change the Item Stack Order

Select some picker items, and press the "CTRL + Up key" to bring them to the top stack order, and the "CTRL + Dn" key to push them down to the bottom stack.

The Picker panel/group is always at the bottom stack order and tends to be covered by other types of picker items.

▪Editing an Existing Image

There are several image properties for a picker item, such as background image for the panel and group, item image for select-button, command-button and slider handle.

At the attribute editor, at the right side of each image path field, there is a > button, click and select "Edit image.." to bring up the image processing dialog.

From v2 you can drag and drop an image to the image path input field to set that as image.

▪Auto-Set a Proper Post Action for Select-Buttons:

Post action is the behavior after the mouse clicks on a select-button in animator mode, you can set it to auto-switch to translate tool, rotate or scale tool or just do nothing.

A proper post-action will save time for animators.

To auto-set, the proper action for selected select-buttons, go to Edit Menu / Auto-Set Sel-Button Post-Actions.

It will test member nodes of each select-button, say if the nodes are all locked in rotate and scale attributes, it will set post action to "Switch to Translate".