Fix: Crash when extra viewport height is zero with sign in view. (#9175)

If a viewport sign straddles the top of a viewport, a crash will occur if the viewport height is zero. This is resolved by simply not attempting to draw the viewport in this situation, consistent with other widgets.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/widget.cpp b/src/widget.cpp
index 68bc43d78..5c1c0ae8f 100644
--- a/src/widget.cpp
+++ b/src/widget.cpp
@@ -2029,6 +2029,8 @@ void NWidgetViewport::SetupSmallestSize(Window *w, bool init_array)
 
 void NWidgetViewport::Draw(const Window *w)
 {
+	if (this->current_x == 0 || this->current_y == 0) return;
+
 	if (this->disp_flags & ND_NO_TRANSPARENCY) {
 		TransparencyOptionBits to_backup = _transparency_opt;
 		_transparency_opt &= (1 << TO_SIGNS) | (1 << TO_LOADING); // Disable all transparency, except textual stuff