kcms/screenedges: Fix buttons overlap on a too narrow vertical screen

BUG: 475579

src/kcms/screenedges/monitor.cpp

@@ -55,6 +55,7 @@ Monitor::Monitor(QWidget *parent)
         m_actionGroups[i] = std::make_unique<QActionGroup>(this);
     }
     QRect avail = screenFromWidget(this)->geometry();
+    setMinimumContentWidth(20 * 3 + 5 * 2); // 3 buttons in a row and some spacing between them
     setRatio((qreal)avail.width() / (qreal)avail.height());
     checkSize();
 }

src/kcms/screenedges/screenpreviewwidget.cpp

@@ -24,6 +24,7 @@ public:
     ScreenPreviewWidgetPrivate(ScreenPreviewWidget *screen)
         : q(screen)
         , ratio(1)
+        , minimumContentWidth(0)
     {
     }
 
@@ -48,6 +49,11 @@ public:
             return;
         }
 
+        const auto minFrameWidth = minimumContentWidth + screenGraphics->marginSize(KSvg::FrameSvg::LeftMargin) + screenGraphics->marginSize(KSvg::FrameSvg::RightMargin);
+        if (monitorSize.width() < minFrameWidth) {
+            monitorSize.setWidth(minFrameWidth);
+        }
+
         monitorRect = QRect(QPoint(0, 0), monitorSize.toSize());
         monitorRect.moveCenter(bounds.center());
 
@@ -63,6 +69,7 @@ public:
     QPixmap preview;
     QRect monitorRect;
     qreal ratio;
+    qreal minimumContentWidth;
     QRect previewRect;
 };
 
@@ -103,6 +110,17 @@ qreal ScreenPreviewWidget::ratio() const
     return d->ratio;
 }
 
+void ScreenPreviewWidget::setMinimumContentWidth(const qreal minw)
+{
+    d->minimumContentWidth = minw;
+    d->updateScreenGraphics();
+}
+
+qreal ScreenPreviewWidget::minimumContentWidth() const
+{
+    return d->minimumContentWidth;
+}
+
 QRect ScreenPreviewWidget::previewRect() const
 {
     return d->previewRect;

src/kcms/screenedges/screenpreviewwidget.h

@@ -24,9 +24,13 @@ public:
 
     void setPreview(const QPixmap &preview);
     const QPixmap preview() const;
+
     void setRatio(const qreal ratio);
     qreal ratio() const;
 
+    void setMinimumContentWidth(qreal minw);
+    qreal minimumContentWidth() const;
+
     QRect previewRect() const;
     KSvg::ImageSet *svgImageSet() const;