Tab view instead of many open windows
SoapUI gives a window for each opened entity (testcase, teststep, request, etc.) and this is good. Only if you have more than 10 windows open, it is really annoying to switch between windows and find the window you want. Instead, it could work with a tab view (one window with a tab for every open window): at the top of the window, a title for each tab (previously: each window) and the option to close this tab (a small cross button). No maximize or minimize buttons, maximized as standard view of the window. Working with tabs is much more organized than lots of windows which you can't get an overview of. By dragging a tab outside the top line with tabs, the tab is moved to a smaller window without tabs (the window-view currently in production).
Tabbed windows, as in modern browsers or Visual Studio
It would be very convenient to work with several windows if they were organized as tabs, as in modern browsers. Now, to quickly switch between windows, you have to reduce their size and change the position of each other so that one window looks out from under the other. See attached screenshot.