Comment 5 for bug 1512175

The issue only show when a scalar unit widget (Inkscape::UI::Widget::ScalarUnit) has the focus. If you first give the focus (by clicking or using the tab key) to the label entry, the color selector, an unit selector or a checkbox, the escape key then quit the dialog as expected.

Other dialogs that use the same widget are also affected (tested with New from template, with DVD Cover and the DVD cover bleed option focused).

A quick workaround could be to give the focus to the Label entry by default so that the issue is not exposed when opening/quitting the dialog with no modification.