kwinrules: Improvements on Detect Properties button

Slight UX and code improvents:

- Disable the detection button when property sheet is open.

- Add a minimum limit (smallDuration) to the delay before detecting
a window. Otherwise we freeze the window before even showing the
button release feedback, which can feel unexpected

- Prefer Q_INVOKABLE over public slot to expose method to QML

kcmkwin/kwinrules/package/contents/ui/RulesEditor.qml

@@ -93,12 +93,16 @@ ScrollViewKCM {
         QQC2.Button {
             text: i18n("Detect Window Properties")
             icon.name: "edit-find"
+            enabled: !propertySheet.sheetOpen
             onClicked: {
-                rulesModel.detectWindowProperties(delaySpin.value);
+                overlayModel.onlySuggestions = true;
+                rulesModel.detectWindowProperties(Math.max(delaySpin.value * 1000,
+                                                           Kirigami.Units.shortDuration));
             }
         }
         QQC2.SpinBox {
             id: delaySpin
+            enabled: !propertySheet.sheetOpen
             Layout.preferredWidth: Kirigami.Units.gridUnit * 8
             from: 0
             to: 30

kcmkwin/kwinrules/rulesmodel.cpp

@@ -809,9 +809,9 @@ QList<OptionsModel::Data> RulesModel::colorSchemesModelData() const
     return modelData;
 }
 
-void RulesModel::detectWindowProperties(int secs)
+void RulesModel::detectWindowProperties(int miliseconds)
 {
-    QTimer::singleShot(secs*1000, this, &RulesModel::selectX11Window);
+    QTimer::singleShot(miliseconds, this, &RulesModel::selectX11Window);
 }
 
 void RulesModel::selectX11Window()

kcmkwin/kwinrules/rulesmodel.h

@@ -76,9 +76,7 @@ public:
     void setDescription(const QString &description);
     QString warningMessage() const;
 
-
-public slots:
-    void detectWindowProperties(int secs);
+    Q_INVOKABLE void detectWindowProperties(int miliseconds);
 
 signals:
     void descriptionChanged();