Allow to specify next window border draw flags

[Teselka]

Hello! This adds an ability to specify next window/child window border draw flags.

2025-11-04.01-43-33.mp4

Usage example:

 ImGuiWindowFlags window_flags = 0;
 if (!has_title_bar)
     window_flags |= ImGuiWindowFlags_NoTitleBar;
 if (has_menu_bar)
     window_flags |= ImGuiWindowFlags_MenuBar;

 static bool has_top_left_border = false;
 static bool has_bottom_left_border = false;
 static bool has_top_right_border = false;
 static bool has_bottom_right_border = false;

 ImDrawFlags border_draw_flags = 0;
 if (has_top_left_border)
     border_draw_flags |= ImDrawFlags_RoundCornersTopLeft;
 if (has_bottom_left_border)
     border_draw_flags |= ImDrawFlags_RoundCornersBottomLeft;
 if (has_top_right_border)
     border_draw_flags |= ImDrawFlags_RoundCornersTopRight;
 if (has_bottom_right_border)
     border_draw_flags |= ImDrawFlags_RoundCornersBottomRight;

 ImGui::SetNextWindowBorderDrawFlags(border_draw_flags);
 ImGui::Begin("Borders Test", 0, window_flags);

 ImGui::Checkbox("Title Bar", &has_title_bar);
 ImGui::Checkbox("Menu Bar", &has_menu_bar);

 ImGui::Checkbox("Top Left", &has_top_left_border);
 ImGui::Checkbox("Bottom Left", &has_bottom_left_border);
 ImGui::Checkbox("Top Right", &has_top_right_border);
 ImGui::Checkbox("Bottom Right", &has_bottom_right_border);

 ImGui::SetNextWindowBorderDrawFlags(border_draw_flags);
 ImGui::BeginChild("Child", ImGui::GetContentRegionAvail(), ImGuiChildFlags_Borders);

 ImGui::TextUnformatted("Child Text!");

 ImGui::EndChild();

[ocornut]

What’s your use case? Why do you need that?
Why not simply disabling the window border and draw one yourself after Begin() ?

[Teselka]

What’s your use case? Why do you need that? Why not simply disabling the window border and draw one yourself after Begin() ?

I'm rendering child window with rounded borders and i want to make specific corner not rounded (in my case left bottom one), drawing it manually every time is not really handful for me

[ocornut]

it manually every time is not really handful for me

I don’t understand what you mean. Isn’t that a single AddRect call to add?

[Teselka]

it manually every time is not really handful for me

I don’t understand what you mean. Isn’t that a single AddRect call to add?

Actually yes + query position/size after Begin(), but you can't do this with root windows

[ocornut]

Well do you have a use case for root windows?

API wise it would make more sense to store this inside the Style struct, e.g. style.WindowRoundingFlags, no reason to introduce ImGuiNextWindowDataFlags_HasBorderDrawFlags, SetNextWindowBorderDrawFlags().

[Teselka]

I agree that it makes more sense to make it a style variable and i guess if nobody needs this one except for me it's not needed to be a part of the imgui