This might be specific to andrzejr/deskbar2 git branch but initial testing showed that the icons are getting correct size allocations, so there may be something else going on underneath. Just after starting up the panel in vertical or deskbar mode, some icons are (sometimes) rendered blank, black or half black. They are all allocated properly and respond to mouse events. Resizing the panel fixes this issue. Log of the start-up process: xfce4-panel(systray): requested cells=0, rows=1, row_size=10, children=0 xfce4-panel(systray): registered manager on screen 0 xfce4-panel(battmon): send provider signal 13 xfce4-panel(external): xfce4-cpufreq-plugin-9: child is embedded; 5 properties in queue xfce4-panel(external): battmon-25: child is embedded; 5 properties in queue xfce4-panel(external): xfce4-mixer-plugin-23: child is embedded; 5 properties in queue xfce4-panel(systray): socket ibus[0x8ff3418] (composited=true, relative-bg=false xfce4-panel(systray): added ibus[0x8ff3418] icon xfce4-panel(external): systray-1: child is embedded; 5 properties in queue xfce4-panel(external): xfce4-orageclock-plugin-17: child is embedded; 5 properties in queue xfce4-panel(external): actions-22: child is embedded; 5 properties in queue xfce4-panel(systray): socket krandrtray[0x8ff3490] (composited=true, relative-bg=false xfce4-panel(systray): added krandrtray[0x8ff3490] icon xfce4-panel(systray): socket skype[0x8ff3508] (composited=true, relative-bg=false xfce4-panel(systray): added skype[0x8ff3508] icon xfce4-panel(systray): socket xfce4-power-manager[0x8ff3580] (composited=true, relative-bg=false xfce4-panel(systray): added xfce4-power-manager[0x8ff3580] icon xfce4-panel(systray): socket networkmanager applet[0x8ff35f8] (composited=true, relative-bg=false xfce4-panel(systray): added networkmanager applet[0x8ff35f8] icon xfce4-panel(systray): socket software-update-available[0x8ff3670] (composited=true, relative-bg=false xfce4-panel(systray): added software-update-available[0x8ff3670] icon xfce4-panel(systray): socket orage[0x8ff36e8] (composited=true, relative-bg=false xfce4-panel(systray): added orage[0x8ff36e8] icon xfce4-panel(systray): requested cells=7, rows=3, row_size=24, children=7 xfce4-panel(systray): allocate rows=3, row_size=24, w=78, h=2, horiz=false, border=1 xfce4-panel(systray): allocated ibus[0x8ff3418] at (2,2;22,22) xfce4-panel(systray): allocated krandrtray[0x8ff3490] at (28,2;22,22) xfce4-panel(systray): allocated networkmanager applet[0x8ff35f8] at (54,2;22,22) xfce4-panel(systray): allocated orage[0x8ff36e8] at (2,28;22,22) xfce4-panel(systray): allocated skype[0x8ff3508] at (28,28;22,22) xfce4-panel(systray): allocated software-update-available[0x8ff3670] at (54,28;22,22) xfce4-panel(systray): allocated xfce4-power-manager[0x8ff3580] at (2,54;22,22) xfce4-panel(systray): allocate rows=3, row_size=24, w=78, h=78, horiz=false, border=1 xfce4-panel(systray): allocated ibus[0x8ff3418] at (2,2;22,22) xfce4-panel(systray): allocated krandrtray[0x8ff3490] at (28,2;22,22) xfce4-panel(systray): allocated networkmanager applet[0x8ff35f8] at (54,2;22,22) xfce4-panel(systray): allocated orage[0x8ff36e8] at (2,28;22,22) xfce4-panel(systray): allocated skype[0x8ff3508] at (28,28;22,22) xfce4-panel(systray): allocated software-update-available[0x8ff3670] at (54,28;22,22) xfce4-panel(systray): allocated xfce4-power-manager[0x8ff3580] at (2,54;22,22) Log of the size allocation after resizing the plugin: xfce4-panel(systray): requested cells=7, rows=3, row_size=24, children=7 xfce4-panel(systray): allocate rows=3, row_size=24, w=78, h=78, horiz=false, border=1 xfce4-panel(systray): allocated ibus[0x90f5580] at (2,2;22,22) xfce4-panel(systray): allocated krandrtray[0x90f5418] at (28,2;22,22) xfce4-panel(systray): allocated networkmanager applet[0x90f5670] at (54,2;22,22) xfce4-panel(systray): allocated orage[0x90f56e8] at (2,28;22,22) xfce4-panel(systray): allocated skype[0x90f5490] at (28,28;22,22) xfce4-panel(systray): allocated software-update-available[0x90f55f8] at (54,28;22,22) xfce4-panel(systray): allocated xfce4-power-manager[0x90f5508] at (2,54;22,22)
Created attachment 4140 (screenshot) Incorrectly rendered systray icons (after start-up)
Created attachment 4141 (screenshot) Correctly rendered systray icons (after resizing the panel)
Comment on attachment 4140 (screenshot) Incorrectly rendered systray icons (after start-up) This screenshot is from a different start-up than the attached log. The one in the log had a completely blank "ibus" icon and a completely black "networkmanager" icon.
Created attachment 6193 Corruption in 4.10.1 I think I'm hitting same or similar problem. As far as I noticed, this usually happens to NetworkManager and Firewall applets. Additional info: Resizing panel by a few px doesn't do anything -- but resizing by a lot brings the icons back to normal.
This report is quite old and there were several newer ones with visual regressions in the systray (which were also handled and mostly fixed), so I'm closing this one too.