QStyleSheet - setting border-image for button also sets background image for its tooltip

I'm having a problem with setting the border-image property of a QToolButton (later on also of a QPushButton but I assume the problem will occur there too). Each of my custom buttons (inheriting from QToolButton and QPushButton respectively) has to have 3 states - inactive, running and error.

Inactive:

style = 'border-top-right-radius: ' + str(self.cornerRadius) + 'px; border-bottom-right-radius: ' + str(self.cornerRadius) + 'px; border-top-left-radius: ' + str(self.cornerRadius) + 'px; border-bottom-left-radius: ' + str(self.cornerRadius) + 'px; border-image: url("' + self.icon  + '"); background: none;'

Running:

style = 'border-top-right-radius: ' + str(self.cornerRadius) + 'px; border-bottom-right-radius: ' + str(self.cornerRadius) + 'px; border-top-left-radius: ' + str(self.cornerRadius) + 'px; border-bottom-left-radius: ' + str(self.cornerRadius) + 'px; border-image: url("' + self.icon  + '"); background: rgb(89, 205, 139);'

Error:

style = 'border-top-right-radius: ' + str(self.cornerRadius) + 'px; border-bottom-right-radius: ' + str(self.cornerRadius) + 'px; border-top-left-radius: ' + str(self.cornerRadius) + 'px; border-bottom-left-radius: ' + str(self.cornerRadius) + 'px; border-image: url("' + self.icon  + '"); background: rgb(215, 56, 56);'

where self.cornerRadius is some number used to determine the roundness of my buttons in pixels and self.icon is an icon I have retrieved from somewhere.

All I do in my button's constructor (among other simple initializations) is

self.setStyleSheet(style)

The clicked() signal of the button is connected to a slot in the same class where the state is changed (along with the style using self.setStyleSheet(...)) in respect to what the system's new state is.

For some unknown reason my tooltip receives the style changes of the button it "belongs to":

I've double-checked the Qt documentation and I see no reason that will explain this behaviour. I do NOT want to change the tooltip's style at all. Any ideas how to fix this?

I interpret the question as:

How to avoid overlapping the style intended for one widget type with another?

Mind that:

• The stylesheet is propagated from parent to child widgets.

• The stylesheet has visibility you can explicitly set for the type.

  ---

  myObj.setStyleSheet("QPushButton {border: 0.05em solid lightgray;}" )

Just enclose the stylesheet with the type e.g. QType { ... }.

I deal only with C++ Qt but think that PyQt uses same stylesheet system.