[LyX/master] Fix crash related to Cursor::macroModeClose().

commit edffc7d6ed372fd3ee2337169470aafb5b18f578
Author: Jean-Marc Lasgouttes <[email protected]>
Date:   Wed Mar 25 12:33:28 2026 +0100

    Fix crash related to Cursor::macroModeClose().
    
    Recipe sent to lyx-devel mailing list: open a new document, press
    Ctrl+M for creating a math box, write '\alpha' into the box, press
    right arrow key.
    
    What happens here is that, in handling of LFUN_CHAR_FORWARD in
    InsetMathNest::doDispatch, Cursor::macroModeClose is invoked (which
    turns \alpha to α) and then the cursor is moved forward. This, in turn,
    will lead to having the lfun undispatched and turned to
    LFUN_FINISHED_FORWARD. The consequence is that the flag Update::Force
    set by macroModeClose is overridden in Cursor::dispatch.
    
    The solution used here is to avoid moving the cursor if macroModeClose
    did something. This is a better behavior anyway. In existing code, if
    one is in a formula before a character and types "\alpha<right>" the
    cursor will jump after the character which is after the alpha. This is
    not nice.
    
    Add a note in Cursor::dispatch that resetting update flags may not be a
    good idea.
    
    The fact that this bug is new to 2.5.x is related to less systematic
    full screen updates in LyX 2.5.x.
---
 src/Cursor.cpp               | 2 ++
 src/mathed/InsetMathNest.cpp | 8 ++++----
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/Cursor.cpp b/src/Cursor.cpp
index b5daf9c860..cc06268483 100644
--- a/src/Cursor.cpp
+++ b/src/Cursor.cpp
@@ -846,6 +846,8 @@ void Cursor::dispatch(FuncRequest const & cmd0)
 			safe.pos() = safe.lastpos();
 		}
 		operator=(safe);
+		// FIXME: should the screen update flags be preserved? After
+		// all an update may have been requested for a reason.
 		disp_.screenUpdate(Update::None);
 		disp_.dispatched(false);
 	} else {
diff --git a/src/mathed/InsetMathNest.cpp b/src/mathed/InsetMathNest.cpp
index aff39557f0..834b5bfbc3 100644
--- a/src/mathed/InsetMathNest.cpp
+++ b/src/mathed/InsetMathNest.cpp
@@ -976,10 +976,10 @@ void InsetMathNest::doDispatch(Cursor & cur, FuncRequest & cmd)
 		// Now that we know exactly what we want to do, let's do it!
 		cur.selHandle(select);
 		cur.clearTargetX();
-		cur.macroModeClose();
-		// try moving forward or backwards as necessary...
-		if (!(forward ? cur.mathForward(word) : cur.mathBackward(word))) {
-			// ... and if movement failed, then finish forward or backwards
+		// Try in order (1) close macromode and (2) move cursor...
+		if (!cur.macroModeClose()
+		     && !(forward ? cur.mathForward(word) : cur.mathBackward(word))) {
+			// ... and both failed, then finish forward or backward
 			// as necessary
 			cmd = FuncRequest(finish_lfun);
 			cur.undispatched();
-- 
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