Launchpad Entry: https://blueprints.launchpad.net/inkscape/+spec/toolbar-resize
The purpose of this blueprint is to give a better organization to the toolbar of inkscape without effecting the space of the workarea itself.
Buttons has been divided by function and shaped/positioned to underline the type of function they shoul do.
Dockable panels are now listed on the right side of the UI, showing all the function that open up a setting box, and inclues also Layers, Text, and Path Effects. All the panels can still be moved outside the dock, resized, reordered as from 0.46.
Tool Controls Bar is now better positioned in the UI to refer better to the tools in the Tools Bar.
Adding new features to a program that should be used by a professional target user, needs also a good study of how the features are used too.
For example, I would expect that buttons that makes the same thing to happen, in this case the buttons that open a box with tool settings, are in the same area of the user interface and have a different look from the other buttons. This would give to the user an easier and more intuitive way to understand features, and to the new user to learn the software.
Also making the user interface more rationale and ordered, making easier to access and to find features and tools, gives to the le software a more professional look in general and improves the user experience.
As first I would try to make a list of the commands and understand the type of reponse the software gives by clicking that specific function. I would make these groups
 simple and direct commands, like "cut", "copy", "open" etc.
 tools with options in a box, as the "trace bitmap" or most of the effects
 tools with options in the "tool controls bar", as "freehand lines" "rectangle" etc
 tools and commands that opens a setting box, as "layers" "stroke and fill" "path effects"
 commands usefull in any situation, suh as "zoom in" or "flip" and that now can be chosen only in the "select" and "zoom" tools
Some of the commands of these groups are shown as buttons in the UI, some are in the tools bar, some in the command bar, but expecially groups 3 and 4 can be marked to give a better affordance of their function. So they should be shown grouped, positioned prompting what they will do after the "click", and have different shape from the other two groups.
Second Step: Different position and shapes
Each group should have a position and a shape that identifies the type of action that it will do (referring to the groups above).
Group 4 should have icons near where the box will appear in the dock on the right, and in Group 3 should be underlined the link between the tool and the "tool controls bar".
Group 5 should have a fixed position or a rollover menu, so that those tools can be used in any time.
Here's an example (a rough mockup)
Thirt Step: Work Space and interaction
All the changes in the UI should have in the end a common goal: save space for the work space. So every box and dialog should be very easy to hide and to popup. I would recommend a button to quicly hide all the boxes and dialogs.
The options of a tool should appear non only when the tool is selected, but when an object of that type is selected too. For example, the text tool options should be visible alse when a text is selected with the selection tool. This means that the options of the selection tool should be always avaliable.
 - Decide the types of commands / functions division
 - Make a list of the commands that fits the division
 - Decide which commands should be shown in the UI (especially for the docked panels)
 - Position and shape of the groups