This review-request introduces a new class named KDualAction. The goal of this class is to make it easy to create a dual-state action: an action which represents two actions, switching from one to the other whenever it is triggered. KDualAction can be used to implement actions such as the Play/Pause action of a media player or the Reload/Stop action of a web browser.
Right now some applications mis-use KToggleAction to implement such dual-state actions: They set the first action as the unchecked state and provide an alternative KGuiItem for the checked state with KToggleAction::setCheckedState(). This is wrong because when the user clicks a button representing the action in a toolbar, the button stays down. The appropriate use cases for toggle buttons (and thus KToggleAction) are documented in a recent addition to the HIG:
http://techbase.kde.org/Projects/Usability/HIG/Toggle_Buttons
Potential users for this class:
- Dragon, Juk, Amarok to implement their Play/Pause action.
- Rekonq to implement its Reload/Stop action. Konqueror could also use this but it does not feature a dual reload/stop action as far as I know.
- Dolphin could maybe use it to implement its Split/Close action (although it's a bit more involved in this case because the close action changes depending on which panel it is going to close)
- Any application which incorrectly uses KToggleAction + setCheckedState() to show/hide a UI element (a search on lxr.kde.org shows quite a lot of misuse: http://lxr.kde.org/ident?i=setCheckedState )
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