Fonts: amend/comment on FontDataOwnedByAtlas=false fix being a breaking change. (#9086, #8465)

imgui.cpp

@@ -394,6 +394,12 @@ IMPLEMENTING SUPPORT for ImGuiBackendFlags_RendererHasTextures:
  When you are not sure about an old symbol or function name, try using the Search/Find function of your IDE to look for comments or references in all imgui files.
  You can read releases logs https://github.com/ocornut/imgui/releases for more details.
 
+ - 2025/11/24 (1.92.6) - Fonts: Fixed handling of `ImFontConfig::FontDataOwnedByAtlas = false` which did erroneously make a copy of the font data, essentially defeating the purpose of this flag and wasting memory.
+                         (trivia: undetected since July 2015, this is perhaps the oldest bug in Dear ImGui history, albeit for a rarely used feature, see #9086)
+                         HOWEVER, fixing this bug is likely to surface bugs in user code using `FontDataOwnedByAtlas = false`.
+                         - Prior to 1.92, font data only needed to be available during the atlas->AddFontXXX() call.
+                         - Since 1.92, font data needs to available until atlas->RemoveFont(), or more typically until a shutdown of the owning context or font atlas.
+                         - The fact that handling of `FontDataOwnedByAtlas = false` was broken bypassed the issue altogether.
  - 2025/11/06 (1.92.5) - BeginChild: commented out some legacy names which were obsoleted in 1.90.0 (Nov 2023), 1.90.9 (July 2024), 1.91.1 (August 2024):
                          - ImGuiChildFlags_Border                    --> ImGuiChildFlags_Borders
                          - ImGuiWindowFlags_NavFlattened             --> ImGuiChildFlags_NavFlattened (moved to ImGuiChildFlags). BeginChild(name, size, 0, ImGuiWindowFlags_NavFlattened) --> BeginChild(name, size, ImGuiChildFlags_NavFlattened, 0)