Extension development / packaging: where to ask questions?

I have a couple of Basic macros that I want to package into an extension. I have questions but don’t know where to ask. This site is for usages questions. The LibreOffice developer list (libreoffice at lists freedesktop org) is, obviously, for development questions. Mine do not fall into either of the categories. The page about mailing lists does not provide any other option and specifically says that the mailing list is intended for All LibreOffice developers and persons interested in LibreOffice development.

Any pointers?

Some background (the first question I need to ask)

I often need to ensure interoperability with Microsoft Office users, thus, to save text documents, spreadsheets and presentations to MSO formats. Using the Save As dialog every time is tedious just to get a copy of a document in a different format, and I want a single-click solution. Years ago, I grabbed some Basic code to export to MSO 97-2003 formats (can’t remember where, perhaps, from oooforum.org), later modified it to export to MSO 2007-365 formats.

Now, I want to have the code packaged as an extension for easier (re)installation and sharing. The extension should install a Basic library and produce a toolbar with two buttons, one for each export option. The toolbar should appear in Writer/Calc/Impress.

Problem: the extension works fine with BMP files for icons but a white background makes the icons fall out of the general UI outlook, however, when I try to replace the files with PNG counterparts, icons are gone, only text appears on the buttons.

In Addons.xcu, I declare the icons as follows:

<prop oor:name="ImageIdentifier" oor:type="xs:string">
     <value>%origin%/icons/export_MSO</value>
 </prop>

and

 <prop oor:name="ImageIdentifier" oor:type="xs:string">
      <value>%origin%/icons/export_MSOX</value>
 </prop>

What can be changed to make PNG files work? I tried to look into several existing extensions. For example, the Alt. Find & Replace extension has:

 <prop oor:name="ImageIdentifier" oor:type="xs:string">
      <value>%origin%/AltSearch/altsearchz</value>
 </prop>

Not different from mine, and the icons are BMP files.

I tried to search for transparent background for toolbar icons in LibreOffice and for PNG files for toolbars of LibreOffice extensions, but did not get useful hits. Should I change the query phrase?

I attach two extension files, one with BMP and one with PNG (the site does not accept .oxt files, so, change .odt for .oxt for installation).

ExportToMSOFormat.odt

ExportToMSOFormat_with_PNG.odt

https://extensions.libreoffice.org/en/extensions/show/multisave-1

Thank you for the pointer. However, the extension does not use a toolbar, it adds a button to an existing toolbar. Thanks anyway!