Tkinter reference: A GUI for Python

19.4 Rules for resource matchingWhen you are creating a widget, and you don’t specify a value for some option, and twoor more resource specifications apply to that option, the most specific one applies.For example, suppose your options file has these two lines:*background: LimeGreen*Listbox*background: FloralWhiteBoth specifications apply to the background option in a Listbox widget, but the secondone is more specific, so it will win.In general, the names in a resource specification are a sequence n 1 ; n 2 ; n 3 ; :::; o where eachn i is a class or instance name. The class names are ordered from the highest to the lowestlevel, and o is the name of an option. However, when Tkinter is creating a widget, all ithas is the class name and the instance name of that widget.Here are the precedence rules for resource specifications:1. The name of the option must match the o part of the option-pattern. For example, ifthe rule isxparrot*indicatoron: 0this will match only options named indicatoron.2. The tight-binding operator (.) is more specific than the loose-binding operator (*).For example, a line for *Button.font is more specific than a line for *Button*font.3. References to instances are more specific than references to classes. For example,if you have a button whose instance name is panicButton, a rule for *panicButton*fontis more specific than a rule for *Button*font.4. A rule with more levels is more specific. For example, a rule for *Button*font ismore specific than a rule for *font.5. If two rules have same number of levels, names earlier in the list are more specificthan later names. For example, a rule for xparrot*font is more specific than a rulefor *Button*font.New Mexico Tech Computer Center Tkinter reference: Standardizing appearance Page 72