ton123123, The intent is to prevent CSS namespace pollution. It is common practice to use a makeshift namespace for your CSS selectors so as not to break existing CSS selectors. Say for example you had a rule for ".closeButton" . If anyone else used that selector in their module, you might be overriding and breaking their CSS. So, you use a makeshift namespace. Let's say everything in your module is inside a container, then you could make that selector ".myModuleContainer .closeButton" and now it will only apply to your module and not break any others.
This is why ".gwt-MenuBar .gwt-MenuItem" is used. There could be ".gwt- MenuItem" items that appear in places other than the menubar, so use this more specific selector to only apply to the menu items of interest. A better step is to use the CSSResource feature of GWT, and then you'll never need to worry about these collisions as each selector can have a unique name, and your CSS will parse faster. https://code.google.com/p/google-web-toolkit/wiki/CssResourceCookbook Hope that helps. Sincerely, Joseph On Feb 29, 10:43 pm, tong123123 <[email protected]> wrote: > in gwt developer > guildehttp://code.google.com/webtoolkit/doc/latest/DevGuideUiCss.html > complex style section: > > .gwt-MenuBar {> /* properties applying to the menu bar itself */ > > } > > .gwt-MenuBar .gwt-MenuItem { > > /* properties applying to the menu bar's menu items */ > > } > > .gwt-MenuBar .gwt-MenuItem-selected { > > /* properties applying to the menu bar's selected menu items */ > > } > > I cannout underatand, why the css rule is > > .gwt-MenuBar .gwt-MenuItem > > but not > > .gwt-MenuItem > ? > I am not good in css, is > .gwt-MenuBar .gwt-MenuItem > is equal to just one css class? not any special meaning for the prefix > .gwt-MenuBar, that is > we can rename it as > .gwt-MenuBargwt-MenuItem will not any different? -- You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-web-toolkit?hl=en.
