Why does the IDE consists of several floating windows (source view, inspector bar, form, main form) ? It's much better if all these components are inside one form (like in regular applications). This makes work a lot easier in multimonitor systems and is also generally clearer. It's not too late to change this.
The IDE and the UI design is borrowed from Delphi/Kylix. If you work with Delphi on Windows, you can use Lazarus on Linux without problems. It is a great UI and easy to use! Even the menu items are almost equal!
With Delphi 8, Borland switched to a new UI similar to MS Visual Studio, but many Delphi developers complain about that: You can not see both code and form at the same time (for example). You can not see the form in whole without scrolling.
The multimonitor support you mentioned is easier to realize with the current UI: Show form designer on first monitor, and code editor on 2nd monitor. If both designer and editor were part of same form, how to display on multi monitors?
Since the Lazarus component library still doesn't support docking (see roadmap[1]), changing the UI by putting all designer windows into one form would be a one-way road. Once the docking has been implemented, you would be able to arrange the IDE forms as you like.
Achim
[1]
http://www.lazarus.freepascal.org/modules.php?op=modload&name=Roadmap&file=index