HButton: add "uncheckable" property

src/gui/Base/HButton.qml

@@ -21,6 +21,7 @@ Button {
     property bool circle: false
     property bool padded: true
     property bool enableRadius: false
+    property bool uncheckable: true
 
     property HToolTip toolTip: HToolTip {
         id: toolTip
@@ -71,4 +72,9 @@ Button {
         when: disableWhileLoading && button.loading
         value: false
     }
+
+    MouseArea {
+        anchors.fill: parent
+        enabled: ! parent.uncheckable && parent.checked
+    }
 }