soffice: Announce keyboard triggered "double underline" toggling (nva…

…ccess#17187)

Implements one aspect from feature requests in nvaccess#6915

Summary of the issue:
Commit 46a3436
("soffice: Report keyboard-triggered formatting toggles in Writer (nvaccess#16413)") implemented announcement of keyboard-triggered formatting changes in LibreOffice Writer, including the one to toggle underline. (When English keyboard layout and UI, the shortcut is Ctrl+B.)

Issue nvaccess#6915 (among others) requests announcement also for "toggle double underline", which is done via the Ctrl+D keyboard shortcut for an English UI.

Description of user facing changes
When toggling double underline in LibreOffice Writer using the corresponding keyboard shortcut, NVDA announces the new state ("double underline on"/"double underline off"). (nvaccess#6915, @michaelweghorn)

Description of development approach
Add Ctrl+D to the list gestures handled by the existing gesture handler.

source/appModules/soffice.py

@@ -538,6 +538,8 @@ def _backspaceScriptHelper(self, unit: str, gesture: inputCore.InputGesture):
 			"kb:control+5",
 			# bold
 			"kb:control+b",
+			# double underline
+			"kb:control+d",
 			# italic
 			"kb:control+i",
 			# underline

user_docs/en/changes.md

@@ -18,6 +18,7 @@ In order to use this feature, the application volume adjuster needs to be enable
 * The add-ons lists in the Add-on Store can be sorted by columns. (#15277, @nvdaes)
 * When decreasing or increasing the font size in LibreOffice Writer using the corresponding keyboard shortcuts, NVDA announces the new font size. (#6915, @michaelweghorn)
 * When applying the "Body Text" or a heading paragraph style using the corresponding keyboard shortcut in LibreOffice Writer 25.2 or newer, NVDA announces the new paragraph style. (#6915, @michaelweghorn)
+* When toggling double underline in LibreOffice Writer using the corresponding keyboard shortcut, NVDA announces the new state ("double underline on"/"double underline off"). (#6915, @michaelweghorn)
 * Automatic language switching is now supported when using Microsoft Speech API version 5 (SAPI5) and Microsoft Speech Platform voices. (#17146, @gexgd0419)
 
 ### Changes