For example, show tray icon only if KVIrc is minimized. And plus add option to "minimize in tray".

I'd like to know if there's option to minimize to tray when clicking minimize button. I know that window can be put to tray when clicking tray icon or when "close to tray" option is on and clicking window close-button.

I use taskbar a lot to minimize programs rather than clicking minimize button (or close button) and I'd like if the window would go to tray when I minimize it using taskbar button.

And a bug report regarding this.

Sometimes when I minimize the window and then restore it by clicking tray icon, it resizes window to something like 640x480 size.
When it happens it's repeatable by minimizing window (either minimize button, or clicking taskbar button to minimize) and then trying to restore it clicking tray icon. This can be "fixed" by maximizing window and clicking tray icon (minimize to tray) and when restored from tray I can again do the thing that bugged and now it works.