Description:
Context: add new icons to the list of icons.
It is possible to add a new icon. It is recognized when importing and can be assigned to a toolbar button, but when reloading the document or module (depending on whether the toolbar is linked to the document or module), the icon is no longer recognized.

Steps to Reproduce:
0. download the attached ImportIcon.odt and icons files (png)
1. Open the attached ImportIcon.odt
2. Right click the 150% button in the PYS custom toolbar (below Default Style listbox), select Customize toolbar
3. Select 150% in the Assigned Commands list
4. Click Modify>Change Icon
5. Click Import> select e.g. mainapp_16.png

The icon is imported (see IconImported.png)

6. Select the icon (to assign it to the button)
7. Click Ok and Ok again to close dialog

Expected & actual result: icon is displayed

8. Save & reload the document: no icon
9. Right click the 150% button,  select Customize toolbar
10. Select 150% in the Assigned Commands list
11. Click Modify>Change Icon

icon is referenced but blank and not assigned (see IconBlank.png)

More information : result is the same with 24x24, 26x26, 32x32

note in the Change dialog says :
the size of an icon should be 24x24 pixels…

The help page says :
You can only import icons that are in the PNG file format and that are 16x16 or 26x26 pixels in size

There is at least one inconsistency between the note and the help page.

Actual Results:



Expected Results:




Reproducible: Always


User Profile Reset: No



Additional Info:
Version: 6.4.2.2 (x64)
Build ID: 4e471d8c02c9c90f512f7f9ead8875b57fcb1ec3
CPU threads: 2; OS: Windows 6.1 Service Pack 1 Build 7601; UI render: default; VCL: win; 
Locale: fr-FR (fr_FR); UI-Language: en-US
Calc: threaded

Also reproduced on https://ask.libreoffice.org/fr/question/237964/icone-de-bouton-qui-disparait/