If you unset the widget tooltip via Widget.setTooltipText or
Widget.setTooltipMarkup, this sets GtkWidget:has-tooltip to FALSE,
which suppresses icon tooltips too. You can resolve this by then calling
Widget.setHasTooltip to set GtkWidget:has-tooltip back to TRUE, or
setting at least one non-empty tooltip on any icon achieves the same result.
Sets tooltip as the contents of the tooltip for the icon at the specified position.
Use NULL for tooltip to remove an existing tooltip.
See also Widget.setTooltipText and Entry.setIconTooltipMarkup.
If you unset the widget tooltip via Widget.setTooltipText or Widget.setTooltipMarkup, this sets GtkWidget:has-tooltip to FALSE, which suppresses icon tooltips too. You can resolve this by then calling Widget.setHasTooltip to set GtkWidget:has-tooltip back to TRUE, or setting at least one non-empty tooltip on any icon achieves the same result.