sddm-theme: focus password field after changing session or kbd layout

We already force focus to the password field after showing or hiding the
virtual keyboard, since otherwise it's annoying and you have to manually
re-focus it. Let's do the same for the session and keyboard layout
choosers to save the user a click and some annoyance.

BUG: 451361
FIXED-IN: 5.25

sddm-theme/KeyboardButton.qml

@@ -32,6 +32,8 @@ PlasmaComponents.ToolButton {
         }
     }
 
+    signal keyboardLayoutChanged
+
     PlasmaComponents.Menu {
         id: menu
         PlasmaCore.ColorScope.colorGroup: PlasmaCore.Theme.NormalColorGroup
@@ -47,6 +49,7 @@ PlasmaComponents.ToolButton {
                 property string shortName: modelData.shortName
                 onTriggered: {
                     keyboard.currentLayout = model.index
+                    keyboardLayoutChanged()
                 }
             }
         }

sddm-theme/Main.qml

@@ -557,11 +557,23 @@ PlasmaCore.ColorScope {
 
             KeyboardButton {
                 font.pointSize: config.fontSize
+
+                keyboardLayoutChanged: {
+                    // Otherwise the password field loses focus and virtual keyboard
+                    // keystrokes get eaten
+                    userListComponent.mainPasswordBox.forceActiveFocus();
+                }
             }
 
             SessionButton {
                 id: sessionButton
                 font.pointSize: config.fontSize
+
+                onSessionChanged: {
+                    // Otherwise the password field loses focus and virtual keyboard
+                    // keystrokes get eaten
+                    userListComponent.mainPasswordBox.forceActiveFocus();
+                }
             }
 
             Item {

sddm-theme/SessionButton.qml

@@ -29,6 +29,8 @@ PlasmaComponents.ToolButton {
         }
     }
 
+    signal sessionChanged
+
     PlasmaComponents.Menu {
         PlasmaCore.ColorScope.colorGroup: PlasmaCore.Theme.NormalColorGroup
         PlasmaCore.ColorScope.inherit: false
@@ -43,6 +45,7 @@ PlasmaComponents.ToolButton {
                 text: model.name
                 onTriggered: {
                     root.currentIndex = model.index
+                    sessionChanged()
                 }
             }
         }