what if we just kept the texture handle away from Rml

rts/Rml/Backends/RmlUi_Renderer_GL3_Spring.cpp

@@ -657,6 +657,10 @@ bool RenderInterface_GL3_Spring::GenerateTexture(Rml::TextureHandle& texture_han
 
 void RenderInterface_GL3_Spring::ReleaseTexture(Rml::TextureHandle texture_handle)
 {
+	// Something was using a texture loaded/managed outside of Rml. Do nothing.
+	if (texture_handle == TextureEnableWithoutBinding)
+		return;
+
 	glDeleteTextures(1, (GLuint*)&texture_handle);
 }
 

rts/Rml/Backends/RmlUi_Renderer_GL3_Spring.h

@@ -76,6 +76,9 @@ class RenderInterface_GL3_Spring : public Rml::RenderInterface {
 	void SetTransform(const Rml::Matrix4f* transform) override;
 
 	// Can be passed to RenderGeometry() to enable texture rendering without changing the bound texture.
+	// Can used as the output of a TextureCallback to signal that this texture is externally managed.
+	//   In that case, you will need to keep a reference to the texture
+	//   you want and bind it before rendering the geometry.
 	static const Rml::TextureHandle TextureEnableWithoutBinding = Rml::TextureHandle(-1);
 
 private: