Alt Shortcuts conflict with dialog mnemonics

Steps to reproduce:

• open Inkscape
• create an object
• open the object properties dialog and dock it (does not happen when floating)
• select the object
• Press Alt+D to create a clone of the object

What happened?

The focus is moved to the "DPI SVG" input box.

What should have happened?

A clone is created.

In general, for this exact reason, shortcuts with Alt should be avoided. (See also #1374 (moved)).

As an easy fix, choose a different letter of DPI SVG for the Alt shortcut.

Also affects the Export PNG dialog ("Document" tab, found a duplicate for that on Launchpad: https://bugs.launchpad.net/inkscape/+bug/1024277).

Also affects the Font dialog ("Set as Default")

Inkscape Version and Operating System:

• Inkscape Version: 1.1-dev (03ae7f7, 2020-01-04)
• Operating System: Windows 10
• Operating System version: 10.0.18362