As a Roblox developer, creating a DockWidgetPluginGui is a very clunky procedure that I think could have been done better.
Right now the configuration is controlled by a data-type used exclusively for this class, called DockWidgetPluginGuiInfo. I have a few general problems with this implementation:
- The type name is quite verbose.
- If you only want to set a specific field of the configuration, you have to pass values to the constructor for all preceding arguments up to the argument corresponding with that field.
-- What's going on here???
local dockWidgetInfo = DockWidgetPluginGuiInfo.new(
Enum.InitialDockState.Left,
false,
false,
0,
0,
0,
120 -- I had to pass default values in for all of the above, just so I could set the MinHeight!
)
- The arguments pertaining to the size of the window when its floating have to be passed in, even if the InitialDockState isn’t set to
Enum.InitialDockState.Float - At a glance, it isn’t obvious what the constructor arguments actually correspond to. You can only figure it out from documentation on the DevHub and existing examples.
So how can this problem be solved? Well, I think it might be worth looking into using a Dictionary instead of an exclusive type. By doing so, you can label the fields of your configuration in Lua, you can list the fields in no specific order, and excluded fields can just fallback to a default value.
-- This is much cleaner!
local dockWidgetInfo =
{
InitialDockState = Enum.InitialDockState.Left;
MinHeight = 120;
}
If the DockWidgetPluginGuiInfo.new constructor is updated to just return a dictionary with the fields set based on what values were passed to it, then the 2nd argument of Plugin:CreateDockWidgetPluginGui could be swapped out for a dictionary!
An interesting thing worth noting is that Plugin:CreateQWidgetPluginGui already uses a dictionary. Perhaps its ahead of its time? 
Function Instance Plugin:CreateQWidgetPluginGui(string pluginGuiId, Dictionary pluginGuiOptions) {RobloxScriptSecurity} [Yields]