Disable inset-dissolve in table cells

This is better than making sure that the inset has exactly one cell.

In the future, inset-dissolve could be extended to dissolve all the
cells contents in the enclosing text.

Note that this check does not appear in mathed, and using dissolve in
e.g. fraction inset may lead to data loss (only current cell contents
is preserved).

(cherry picked from commit 5ac3b88007)

src/insets/InsetTabular.cpp

@@ -3588,6 +3588,9 @@ bool InsetTableCell::getStatus(Cursor & cur, FuncRequest const & cmd,
 {
 	bool enabled = true;
 	switch (cmd.action()) {
+	case LFUN_INSET_DISSOLVE:
+		enabled = false;
+		break;
 	case LFUN_MATH_DISPLAY:
 		if (!hasFixedWidth()) {
 			enabled = false;

src/insets/InsetText.cpp

@@ -318,10 +318,8 @@ void InsetText::doDispatch(Cursor & cur, FuncRequest & cmd)
 		bool const main_inset = text_.isMainText();
 		bool const target_inset = cmd.argument().empty()
 			|| cmd.getArg(0) == insetName(lyxCode());
-		// cur.inset() is the tabular when this is a single cell (bug #9954)
-		bool const one_cell = cur.inset().nargs() == 1;
 
-		if (!main_inset && target_inset && one_cell) {
+		if (!main_inset && target_inset) {
 			// Text::dissolveInset assumes that the cursor
 			// is inside the Inset.
 			if (&cur.inset() != this)
@@ -351,11 +349,9 @@ bool InsetText::getStatus(Cursor & cur, FuncRequest const & cmd,
 		bool const main_inset = text_.isMainText();
 		bool const target_inset = cmd.argument().empty()
 			|| cmd.getArg(0) == insetName(lyxCode());
-		// cur.inset() is the tabular when this is a single cell (bug #9954)
-		bool const one_cell = cur.inset().nargs() == 1;
 
 		if (target_inset)
-			status.setEnabled(!main_inset && one_cell);
+			status.setEnabled(!main_inset);
 		return target_inset;
 	}
 

status.23x

@@ -159,6 +159,8 @@ What's new
 
 - Enable dissolve in undefined Flex inset context menu (bug 8650).
 
+- Enable dissolve in context menu of element in table cells.
+
 - Fix bad caret position when row scrolls horizontally (bug 11603).
 
 - Fix crash when inserting some insets in math split insets  (bug 11686).