The WindowManager plugin provides a controller for several different types of window groups. HTML UIs added to these WindowManager groups will be arranged and managed in accordance with each group's purpose.
One group type is "Dock View". Both WebChat and SendMessage utilize this group to show their toast-like UI docked in the lower-bottom-right of the screen. This group automatically arranges the two widgets stacked horizontally and when one widget closes, the stack collapses towards the right. Widgets can register themselves into these WindowManager groups and let it do all the work.
Another group type is "Side Button". WebChat and SendMessage also utilize this group to show their launcher buttons on the right side of the screen. Like the dock view, buttons are stacked, but in this case they are stacked vertically. As buttons are added and removed from the group, the button stack will collapse to fill in the gaps.
WindowManager has "register" commands for registering your UI into different groups. They all accept one argument, the HTML you want to be handled by WindowManager. You can use 'registerDockView' or 'registerSideButton' at this time. More window management groups will be added in upcoming releases.
Toaster does not have customization options.