Description:
Environment = Ubuntu 16.04 & Firefox 58 & LibreOffice Impress Version: 5.3.7.2 & 5.1.X.X

When a slide from Impress 5.1.x.x is exported as *.SVG, a thumbnail image was generated.
This thumbnail image could be viewed in the default file manager for Ubuntu when viewing criteria was set to "Display a Grid of Icons".
The *.SVG could be opened in the default viewer application called "Image Viewer" and would display the *.SVG image.

As of LibreOffice Impress Version 5.3.7.2, no thumbnail image is generated and the *.svg file cannnot be viewed in Image Viewer.

A *.SVG file generated by either 5.1.X.X & 5.3.X.X can be viewed by FireFox web browser.

Note: the *.SVG does not validate when submitted to: "https://validator.w3.org/#validate_by_upload+with_options"

Steps to Reproduce:
1) Start a New Impress *.odp
2) Do anything such as type text, insert an image etc.
3) File > Save
4) File > Export > SVG
5) Try to open the *.SVG with Image Viewer and enjoy the system lock-up followed by application crash 

Actual Results:  
 - no thumbnail image generated
 - image cannot be opened by Ubuntu default application = Image Viewer
 - image cannot be opened by Ubuntu default file browser = Nautilus

Expected Results:
 - in 5.1 everything worked as expected
 - in 5.3 it will crash the application but not the OS


Reproducible: Always


User Profile Reset: No



Additional Info:
Impress is not handling many aspects of *.SVG export correctly
The entire module needs to be reviewed.


User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:58.0) Gecko/20100101 Firefox/58.0