multi-screen: find view::screen id in better way

--when monitor from an explicit screen was closed there
were cases that docks were moved at another monitor from
the window manager and that was preventing them to be
delete properly. This patch fixes this by considering
as valid explicit screen only the one provided by the
view

BUG: 405687

app/layout.cpp

@@ -1505,20 +1505,29 @@ void Layout::syncDockViewsToScreens()
     //! first step: primary docks must be placed in primary screen free edges
     foreach (auto containment, m_containments) {
         if (isLatteContainment(containment)) {
-            int screenId = containment->screen();
+            int screenId = 0;
 
-            if (screenId == -1) {
-                screenId = containment->lastScreen();
+            //! valid screen id
+            if (latteViewExists(containment)) {
+                screenId = m_latteViews[containment]->positioner()->currentScreenId();
+            } else {
+                screenId = containment->screen();
+
+                if (screenId == -1) {
+                    screenId = containment->lastScreen();
+                }
             }
 
             bool onPrimary{true};
 
+            //! valid onPrimary flag
             if (latteViewExists(containment)) {
                 onPrimary = m_latteViews[containment]->onPrimary();
             } else {
                 onPrimary = containment->config().readEntry("onPrimary", true);
             }
 
+            //! valid location
             Plasma::Types::Location location = containment->location();
 
             if (onPrimary && !futureDocksLocations[prmScreenName].contains(location)) {
@@ -1531,20 +1540,29 @@ void Layout::syncDockViewsToScreens()
     //! second step: explicit docks must be placed in their screens if the screen edge is free
     foreach (auto containment, m_containments) {
         if (isLatteContainment(containment)) {
-            int screenId = containment->screen();
+            int screenId = 0;
 
-            if (screenId == -1) {
-                screenId = containment->lastScreen();
+            //! valid screen id
+            if (latteViewExists(containment)) {
+                screenId = m_latteViews[containment]->positioner()->currentScreenId();
+            } else {
+                screenId = containment->screen();
+
+                if (screenId == -1) {
+                    screenId = containment->lastScreen();
+                }
             }
 
             bool onPrimary{true};
 
+            //! valid onPrimary flag
             if (latteViewExists(containment)) {
                 onPrimary = m_latteViews[containment]->onPrimary();
             } else {
                 onPrimary = containment->config().readEntry("onPrimary", true);
             }
 
+            //! valid location
             Plasma::Types::Location location = containment->location();
 
             if (!onPrimary) {