I knew that Firefox was not supported by FMP(A) 14 and FMS14.
However, I never knew why, because our complex FM14 WebDirect application seemed to work fine.
In just a layout the tab order which worked fine in all other layouts crashes the web session.
I spent hours to search for the cause, until I came to the idea to see whether the same layout also crashed in Microsoft 10 Edge.
It did not, no problem at all in the same layout.
And another observation in Firefox: the alignment of texts in fields is not always as it should be.
Texts which should stand in the middle are set on top or bottom position in that field.
I have to accept that Filemaker will not support Firefox.
I think that's strange because Firefox is a very well performing browser, better that Chrome.
I hear from many people that the newest Chrome release-update crashes constantly.
So, back to good old Microsoft then ....
Firefox does not implement HTML 5 the same way as the supported browsers