Qt 6.11 is out! See what's new in the release
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I cannot use the design studio totally
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I've closed the windows of it,below is what it looks like

I cannot restore default settings.@hdugzx I never used Design Studio, but there should be a menu like "View" or "Windows". Look in "..." in the top-right corner. You also can check the settings. In QtCreator you can disable/enable menu by pressing Ctrl-Alt-m - maybe it also works in Design Studio.