CssFontHelper get an array of CSS class names with same "content" rule
From FontAwesome CSS it returns for example 
From IntranetIcon.css it returns for example 
From Material Icon css it returns for example 
All items of the array of class names are supposed to be enought to display the glyph, so in ChooseGlyph widget, only the first class of the array is used
new Ext.XTemplate(
'<tpl for=".">',
'<div class="data-view-glyph-icon">',
'<div class="glyph-icon-class {[values.cssClassNames[0]]}" title="{[values.cssClassNames.join(\'\\n\')]}"></div>',
'</div>',
'</tpl>'
)
Sol 1: Use values.cssClassNamesAsString in XTemplate in widget
Sol 2: Fix CssFontHelper to be able to handle CSS such as material icons. It should returns a array of one item only "material-icons g_translate"
CSS of material icon:
.material-icons {
font-family: 'Material Icons';
font-weight: normal;
font-style: normal;
font-size: 24px;
display: inline-block;
line-height: 1;
text-transform: none;
letter-spacing: normal;
word-wrap: normal;
white-space: nowrap;
direction: ltr;
-webkit-font-smoothing: antialiased;
text-rendering: optimizeLegibility;
-moz-osx-font-smoothing: grayscale;
font-feature-settings: 'liga';
}
.material-icons.3d_rotation:before {
content: "\e84d";
}
Sol 1 can not work...
For example for IntranetIcon we have "ametysicon-xxx" and "decorator-ametysicon-xxx" that use the same content rule but one with :before, the other with :after. So the icon will be displayed twice