When using the "Vertex-Dark" theme, buttons in GTK2 applications will have their size changed temporarily while hovered. They extend by 1px to each site horizontally while in hover (prelight) state.
Look closely at this animated screen capture (GIF):
The only clue I got right now is that the PNG button assets sizing differ between the normal and the "Dark" theme variant:
Vertex (normal):
button texture sizes: 18x18 px
Vertex-Dark:
varying between either 16x16 or 18x16 px, e.g.:
button-prelight.png: 16x16 px
button-default.png: 18x16 px
(based on common/gtk-2.0/Buttons/ and common/gtk-2.0-dark/Buttons/
Running Xfce 4.12 on Debian 8.6, using the latest tag of the theme from GitHub.
gtk2-engines-pixbuf v2.24.25-3
libgtk2.0 v2.24.25-3
When using the "Vertex-Dark" theme, buttons in GTK2 applications will have their size changed temporarily while hovered. They extend by 1px to each site horizontally while in hover (prelight) state.
Look closely at this animated screen capture (GIF):
The only clue I got right now is that the PNG button assets sizing differ between the normal and the "Dark" theme variant:
button-prelight.png: 16x16 pxbutton-default.png: 18x16 px(based on
common/gtk-2.0/Buttons/andcommon/gtk-2.0-dark/Buttons/Running Xfce 4.12 on Debian 8.6, using the latest tag of the theme from GitHub. gtk2-engines-pixbuf v2.24.25-3 libgtk2.0 v2.24.25-3