"For instance maybe you could decide to display the sidebar label next to its icon if you consider that the corresponding icon doesn't provide a good enough metaphor (see Midori for a sidebar icon exemple) (but it's not the reason why "priority text" setting exist...)
However there could be some i18n problems : for instance "sidepane" would be translated "panneau latéral" in french and that would make a huge button"
Totem 2.28 toolbar doesn't follow GNOME Style either, but i've noticed that it has a "sidepane" (or maybe just "pane" - i don't run the english version) button with only the label (without icon) whereas other buttons have only an icon.
Developpers may have good reason to go against HIG sometimes : i guess they didn't find any good metaphor for the sidepane and therefore have renounced to display an icon.
I think you have the choice in "text beside icons" mode for the sidebar : displaying only an icon, or an icon plus a label, or only a label
Note that, in french, the (side)pane button is translated into "panneau" (and not "panneau latéral") which avoids to have huge buttons in the toolbar
"For instance maybe you could decide to display the sidebar label next to its icon if you consider that the corresponding icon doesn't provide a good enough metaphor (see Midori for a sidebar icon exemple) (but it's not the reason why "priority text" setting exist...)
However there could be some i18n problems : for instance "sidepane" would be translated "panneau latéral" in french and that would make a huge button"
Totem 2.28 toolbar doesn't follow GNOME Style either, but i've noticed that it has a "sidepane" (or maybe just "pane" - i don't run the english version) button with only the label (without icon) whereas other buttons have only an icon.
Developpers may have good reason to go against HIG sometimes : i guess they didn't find any good metaphor for the sidepane and therefore have renounced to display an icon.
I think you have the choice in "text beside icons" mode for the sidebar : displaying only an icon, or an icon plus a label, or only a label
Note that, in french, the (side)pane button is translated into "panneau" (and not "panneau latéral") which avoids to have huge buttons in the toolbar