[feat] make MainWindow and ServerWindow use rounded corners

src/common/rounded_corner_button.cpp

@@ -0,0 +1,63 @@
+#include "rounded_corner_button.h"
+
+namespace crossdesk {
+bool RoundedCornerButton(const char* label, const ImVec2& size, float rounding,
+                         ImDrawFlags round_flags, bool enabled,
+                         ImU32 normal_col, ImU32 hover_col, ImU32 active_col,
+                         ImU32 border_col) {
+  ImGuiWindow* current_window = ImGui::GetCurrentWindow();
+  if (current_window->SkipItems) return false;
+
+  const ImGuiStyle& style = ImGui::GetStyle();
+
+  ImGuiID button_id = current_window->GetID(label);
+  ImVec2 cursor_pos = current_window->DC.CursorPos;
+  ImVec2 button_size = ImGui::CalcItemSize(size, 0.0f, 0.0f);
+  ImRect button_rect(cursor_pos, ImVec2(cursor_pos.x + button_size.x,
+                                        cursor_pos.y + button_size.y));
+  ImGui::ItemSize(button_rect);
+  if (!ImGui::ItemAdd(button_rect, button_id)) return false;
+
+  bool is_hovered = false, is_held = false;
+  bool is_pressed = false;
+  if (enabled) {
+    is_pressed =
+        ImGui::ButtonBehavior(button_rect, button_id, &is_hovered, &is_held);
+  }
+
+  if (normal_col == 0) normal_col = ImGui::GetColorU32(ImGuiCol_Button);
+  if (hover_col == 0) hover_col = ImGui::GetColorU32(ImGuiCol_ButtonHovered);
+  if (active_col == 0) active_col = ImGui::GetColorU32(ImGuiCol_ButtonActive);
+  if (border_col == 0) border_col = ImGui::GetColorU32(ImGuiCol_Border);
+
+  ImU32 fill_color = normal_col;
+  if (is_held && is_hovered)
+    fill_color = active_col;
+  else if (is_hovered)
+    fill_color = hover_col;
+
+  if (!enabled) fill_color = IM_COL32(120, 120, 120, 180);
+
+  ImDrawList* window_draw_list = ImGui::GetWindowDrawList();
+
+  window_draw_list->AddRectFilled(button_rect.Min, button_rect.Max, fill_color,
+                                  rounding, round_flags);
+
+  if (style.FrameBorderSize > 0.0f) {
+    window_draw_list->AddRect(button_rect.Min, button_rect.Max, border_col,
+                              rounding, round_flags, style.FrameBorderSize);
+  }
+
+  ImU32 text_color =
+      ImGui::GetColorU32(enabled ? ImGuiCol_Text : ImGuiCol_TextDisabled);
+
+  const char* label_end = ImGui::FindRenderedTextEnd(label);
+  ImGui::PushStyleColor(ImGuiCol_Text,
+                        ImGui::ColorConvertU32ToFloat4(text_color));
+  ImGui::RenderTextClipped(button_rect.Min, button_rect.Max, label, label_end,
+                           nullptr, ImVec2(0.5f, 0.5f), &button_rect);
+  ImGui::PopStyleColor();
+
+  return is_pressed;
+}
+}  // namespace crossdesk

src/common/rounded_corner_button.h

@@ -0,0 +1,20 @@
+/*
+ * @Author: DI JUNKUN
+ * @Date: 2026-02-26
+ * Copyright (c) 2026 by DI JUNKUN, All Rights Reserved.
+ */
+
+#ifndef _ROUNDED_CORNER_BUTTON_H_
+#define _ROUNDED_CORNER_BUTTON_H_
+
+#include "imgui.h"
+#include "imgui_internal.h"
+
+namespace crossdesk {
+bool RoundedCornerButton(const char* label, const ImVec2& size, float rounding,
+                         ImDrawFlags round_flags, bool enabled = true,
+                         ImU32 normal_col = 0, ImU32 hover_col = 0,
+                         ImU32 active_col = 0, ImU32 border_col = 0);
+}  // namespace crossdesk
+
+#endif