Put drawing first in the folio's context menu, rows and columns one level down

Right-clicking an empty folio offered Paste here, Folio properties and
four row/column actions. Four of six entries change the folio's layout,
which is rarely wanted and easy to hit by mistake, while nothing in the
menu helps draw.

The empty-folio menu now holds the "Ajouter" submenu (text, image,
shapes, terminal strip plan -- the same actions as the Edition menu and
toolbar), then Folio properties, then the row and column actions in a
"Lignes et colonnes" submenu. The selection menu is unchanged.

A submenu whose actions are all disabled is dropped, the same way
disabled actions already are.

Discussion #1033.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01G2d2Zi8BfrYRPX88zhaoFG

sources/diagramview.cpp

@@ -43,6 +43,7 @@
 #include <QDropEvent>
 #include <QPainter>
 #include <QPointer>
+#include <algorithm>
 
 /**
 	Constructeur
@@ -1299,10 +1300,15 @@ QList<QAction *> DiagramView::contextMenuActions() const
 	{
 		if (m_diagram->selectedItems().isEmpty())
 		{
+				//Drawing comes first. The row and column actions change
+				//the folio's layout and are rarely wanted, so they sit one
+				//level down where a stray click cannot reach them.
 			list << m_paste_here;
 			list << m_separators.at(0);
+			list << qde->m_add_item_menu->menuAction();
+			list << m_separators.at(1);
 			list << qde->m_edit_diagram_properties;
-			list << qde->m_row_column_actions_group.actions();
+			list << qde->m_row_column_menu->menuAction();
 		}
 		else
 		{
@@ -1318,11 +1324,19 @@ QList<QAction *> DiagramView::contextMenuActions() const
 			list << qde->m_depth_action_group->actions();
 		}
 
-			//Remove from the context menu the actions which are disabled.
+			//Remove from the context menu the actions which are disabled,
+			//and the submenus in which every action is disabled.
 		const QList<QAction *> actions = list;
 		for(QAction *action : actions)
 		{
-			if (!action->isEnabled()) {
+			bool usable = action->isEnabled();
+			if (usable && action->menu())
+			{
+				const QList<QAction *> sub_actions = action->menu()->actions();
+				usable = std::any_of(sub_actions.cbegin(), sub_actions.cend(),
+									 [](QAction *a) { return a->isEnabled(); });
+			}
+			if (!usable) {
 				list.removeAll(action);
 			}
 		}

sources/qetdiagrameditor.cpp

@@ -1044,9 +1044,9 @@ void QETDiagramEditor::setUpMenu()
 		//toolbar button has no key, so text fields, images and every drawing
 		//shape simply could not be added. m_depth_action_group below has
 		//always been in both places; this brings these into line with it.
-	QMenu *menu_add_item = menu_edition -> addMenu(tr("A&jouter"));
-	menu_add_item -> setIcon(QET::Icons::Add);
-	menu_add_item -> addActions(m_add_item_actions_group.actions());
+	m_add_item_menu = menu_edition -> addMenu(tr("A&jouter"));
+	m_add_item_menu -> setIcon(QET::Icons::Add);
+	m_add_item_menu -> addActions(m_add_item_actions_group.actions());
 	menu_edition -> addSeparator();
 	menu_edition -> addActions(m_select_actions_group.actions());
 	menu_edition -> addSeparator();
@@ -1056,6 +1056,12 @@ void QETDiagramEditor::setUpMenu()
 	menu_edition -> addSeparator();
 	menu_edition -> addAction(m_edit_diagram_properties);
 	menu_edition -> addActions(m_row_column_actions_group.actions());
+		//Not added to a menu here: it exists so the folio's context menu can
+		//hold the row and column actions one level down (see
+		//DiagramView::contextMenuActions()).
+	m_row_column_menu = new QMenu(tr("Lignes et colonnes"), this);
+	m_row_column_menu -> setIcon(QET::Icons::EditTableInsertColumnRight);
+	m_row_column_menu -> addActions(m_row_column_actions_group.actions());
 	menu_edition -> addSeparator();
 	menu_edition -> addActions(m_depth_action_group->actions());
 	menu_edition -> addSeparator();

sources/qetdiagrameditor.h

@@ -177,6 +177,10 @@ class QETDiagramEditor : public QETMainWindow
 		m_row_column_actions_group, /// Action related to add/remove rows/column in diagram
 		m_selection_actions_group,  ///Action related to edit a selected item
 		*m_depth_action_group = nullptr;
+
+		QMenu
+		*m_add_item_menu = nullptr,   ///< Submenu of m_add_item_actions_group
+		*m_row_column_menu = nullptr; ///< Submenu of m_row_column_actions_group
 	
 	private:
 		QActionGroup