It would be nice if tabs, frames, rectangles, etc. supported background colors. It would be even better if the sktch-mode rendering of the colors supported the same hand-drawn style as other stencils ie. a chalk-like scribble of color.

At the momen I see if someone else is working on a usecase or page. I can't see who and I can't contact him/her. A Livechat on the prototype would be great.

Provide movable guide lines (auxiliary lines) to help align elements more easily.

I am using custom stencils for connectors in a graph-like structure.

At the moment, I need to (re-)upload the stencils with proper rotation, especially when things change. It would be nice if I could rotate the existing stencil instead.

Showing all the arrows makes system sluggish and makes it very hard to sort or resize screens etc.! I never use the arrow tools to edit an connection, anyway ... Why not allow toggling between views with/without connections. Should be a feature not too hard to implement :-)

text on tabs is centered, it should be able to be left justified

The layer bar might be confusing, when many layers are used. It should be able to collect them in different folders.

...without having to use the wiki syntax. E.g. offer individual cells to write text into and let users select table size in context menu via specifying number of rows and columns.

Show full pagename on pages view (long names are truncated) making navigation hard.
And also extend Target to show full pagename

I want to send a proto out to a group to have a group review. I'd like to have a Review Pane where the entire discussion is displayed with a comment entry form (standard UI for threaded discussion). So the group can read the discussion and add to it as needed. Look at basecamp messages for inspiration.

please make pages within a usecase sortable

It's confusing for some recipients to see the dark spots in the export.

To use it within our org. we would like to let people login with their own account. It would be nice to setup something like 10 users within the expert account and create there own mockups. This way the top account has an overview over all projects running.

maybe uml2 activity diagram

I think delete option should be visible somewhere on a map http://prntscr.com/le1wq3. I spent much time while looking for this option.

want to add an expiry date for invitation links thus my clients have not access all the time

Add an drop down arrow to denote content that shows up conditionally from clicking on a button or accordion sliders.