CSS 未被 Eclipse e4 使用

Question

I want to use CSS styling for some widgets in only one plugin of my application.

The Plugin's plugin.xml contains:

<extension
  point="org.eclipse.e4.ui.css.swt.theme">
    <theme
        basestylesheeturi="css/default.css"
        id="my.app.id.css"
        label="Planning Theme">
    </theme>
 </extension>

The Plugin.xml's extension tab didn't suggest the extension point, but after I entered it in the file, I could see the properties. One of which is "basestylesheeturi" and it allows me to browse for the file. So the file definitely exists.

@charset "ISO-8859-1";

#MYTESTLABEL{
    color: blue;
}

Text {
    color: COLOR-CYAN;
    background-color: COLOR-WIDGET-BACKGROUND;
}

Button {
 font: Verdana 24px; 
 border-color: #EEEE00;
 border-width: 2;
}

But it isn't used by Eclipse. When I start my Application, I cannot see any styles from the css file. Setting colors to black or fonts to huge sizes... nothing has an effect. Even Syntax Errors in the css file won't result in an error message.

What can I do to ensure my plugin uses this css file for Texts, Buttons, etc.? Is my old Eclipse version maybe not supporting the extension point?

Version: Oxygen.3 Release (4.7.3)

EDIT

If I understand greg's answer correctly, I have to use both extension points ( org.eclipse.core.runtime.product and org.eclipse.e4.ui.css.swt.theme ). Additionally I added the css/default.css to the bin.includes section of the build.properties. The style is still not used.

There is a cssTheme already defined in another plugin.xml for the product by using those two extension points. From my understanding it should be possible to define a second theme only for a certain plugin.

It may be that I need to implement a ThemeSwitchHandler as vogella describes here but it's unclear how to make use of it (how and when to call it).

Answer 1

That extension point just defines a theme, it doesn't tell e4 to use it.

For a pure e4 RCP you specify the theme to be used in the cssTheme property of the org.eclipse.core.runtime.products extension point which defines your product:

 <extension
       id="product"
       point="org.eclipse.core.runtime.products">
    <product
          name="%product.name"
          application="org.eclipse.e4.ui.workbench.swt.E4Application">
        <property
             name="cssTheme"
             value="my.app.id.css">
        </property>
        ... other properties

If there is already a theme defined in the RCP you can contribute an extra stylesheet file to the theme. For example:

<extension
       point="org.eclipse.e4.ui.css.swt.theme">
   <stylesheet
         uri="css/e4-dark_pde_prefstyle.css">
      <themeid
            refid="org.eclipse.e4.ui.css.theme.e4_dark">
      </themeid>
   </stylesheet>
</extension>

Which adds an extra file to the standard Eclipse org.eclipse.e4.ui.css.theme.e4_dark dark theme.