In "Explorer" moving things to be sub items of diagrams seems to be a single item at a time experience (unless i missed anything.) Would save time to be able to control-click or shift-click to select multiple items in explorer to move.

Zoom with Ctrl+mouse wheel
Reset zoom with ctr+/ or *

I'm from a non english speaking country and I'd like to see a spanish version of StarUML. And I think there are a lot of people from non english speaking country who are expecting for a spanish version of the software, too.

Full screen mode for the workspace and separately for the workspace with instrument panels.

Making a const method I check the 'isQuery' in property menu and the result shown in class diagram with '{query}'.
But, writing the '{query}' in diagram cannot make the 'isQuery' property checked. How about applying this usability? The class diagram checks the user inputs. So, I thought it is a kind of such evaluation process. And, in my opinion, other properties could be applied like that.

Add a command palette like in modern developer/conceptor tools (like SublimeText, Atom, VSCode, ...) for a quick access to all available commands.

See VSCode : https://code.visualstudio.com/docs/getstarted/userinterface#_command-palette

One of the cardinal rules of documentation is always have a legend. See e.g. Documenting Software Architectures. It would be nice to have the option to create a legend. Bonus points if StarUML can automatically generate the legend based on UML elements in the diagram.

We can change the diagram background color, but not the editor background color. This is by far my biggest complaint with the tool and the one thing holding my team back from adopting it.

To be clear, I'm referring to the area of the tool with the grid background. The one that displays all of your diagrams.

It would be nice if a usecase descriptions can split in multiple requirement-items. Each items needs a short text field.

I'd really like to see an option to lock a specific UML element to the workspace, so that if someone is making a namespace and has a lot of sub name spaces to move around they can avoid clicking on the containing one. I'm not sure how often people run into this when working with it, but I've found it somewhat vexing.

We should be able to, for example, double-click on "Attribute1" to select it, then right-click to paste from keyboard. It is possible to paste using Ctrl-V, but doing that many times gets annoying.

Add F2 for 'in-place' rename at least in Model Explorer.

Use case:
- Bob wants to rename element MyFirstClass in the model explorer
- Bob browse for MyFirstClass element in the Model Explorer
- Bob press F2 when on the MyFirstClass and in-place renames that element to MySecondClass

Is there a downloadable user's manual for StarUML?

how to convert a sequence diagram into a communication diagram (collaboration diagram)?

Would be great if there was an extension for visual studio

It would be nice if a usecase descriptions can split in multiple step-items. Each items needs a short text field.