4) There's a number of palettes provided with inkscape. If they are all displayed in tree mode, they occupy a lot of 

space in swatches dialog [1]. It can be quite uncomfortable to use "Ubuntu" and "Current document" palettes

at the same time. In grid view mode, when all categories are collapsed into one, the situation is even worse [2].

   

I can think of three solutions:

* Leave tree mode [1] as is and in grid mode [2] display only expanded palettes. To enhance discoverability

  it would be possible to expand and close palettes from popup menu [3]

* Use the popup menu [3] to choose palettes that are shown in swatches dialog. If a category is shown it can

  further be expanded or collapsed.

* Share a TreeModel behind swatches dialog between: patterns panel in fill and stroke dialog, color chooser bar

  at the bottom of the screen and swatches dialog. Add a dialog to choose active palettes, as shown in [4]. The

  solution is similar to GIMP behaviour.

Which of them do you like most?

In third case we have a data model common to a number of dialogs. How can I implement creating and sharing

the object? What comes to my mind is making the data model a singleton, or associating it with SPDesktop 

object. Are there other possibilities?