A simple, small calculator placed discreetly near the Windows Taskbar or anywhere on the screen
feat: persist window position, anchor above tray on first run, survive Explorer restart
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Marco Maroni
(Jul 14, 2026, 3:23 PM +0200)
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App.cpp
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App.cpp
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wc.lpszClassName = L"TaskbarCalculatorOwner";
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RegisterClassW(&wc);
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HWND owner = CreateWindowW(wc.lpszClassName, L"", 0, 0, 0, 0, 0,
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HWND_MESSAGE, nullptr, hInst, nullptr);
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// Hidden top-level tool window (no taskbar button) so it still receives
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// the broadcast "TaskbarCreated" message when Explorer restarts.
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HWND owner = CreateWindowExW(WS_EX_TOOLWINDOW, wc.lpszClassName, L"",
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WS_POPUP, 0, 0, 0, 0, nullptr, nullptr, hInst, nullptr);
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g_tray.Add(owner, WM_TRAY_CALLBACK, TRAY_ICON_ID, L"Taskbar Calculator");
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+30
CalculatorWindow.cpp
+30
CalculatorWindow.cpp
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#include "VisualStyle.h"
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#include "Utils.h"
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#include "Calculator.h"
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#include "Settings.h"
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////////////////////////////////////////////////////////////////////////////////
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//
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POINTL ideal = CalcIdealSize();
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SetWindowPos(NULL, 0, 0, ideal.x + 24, ideal.y + 16, SWP_NOMOVE | SWP_NOZORDER);
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PlaceInitial();
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return TRUE;
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}
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void CCalculatorWindow::PlaceInitial()
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{
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RECT wr; GetWindowRect(&wr);
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int w = wr.right - wr.left, h = wr.bottom - wr.top;
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POINT pt;
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if (Settings::LoadWindowPos(pt)) {
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SetWindowPos(NULL, pt.x, pt.y, 0, 0, SWP_NOSIZE | SWP_NOZORDER);
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return;
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}
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// First run: anchor bottom-right, just above the notification area.
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APPBARDATA abd{}; abd.cbSize = sizeof(abd);
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RECT work; SystemParametersInfo(SPI_GETWORKAREA, 0, &work, 0);
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int x = work.right - w - 8;
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int y = work.bottom - h - 8;
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if (SHAppBarMessage(ABM_GETTASKBARPOS, &abd)) {
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if (abd.rc.top > work.top) y = abd.rc.top - h - 8;
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}
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SetWindowPos(NULL, x, y, 0, 0, SWP_NOSIZE | SWP_NOZORDER);
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}
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void CCalculatorWindow::ToggleVisible()
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// Allow dragging the window by its body.
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ReleaseCapture();
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SendMessage(WM_NCLBUTTONDOWN, HTCAPTION, 0);
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return 0;
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}
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LRESULT CCalculatorWindow::OnExitSizeMove(UINT, WPARAM, LPARAM, BOOL&)
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{
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RECT wr; GetWindowRect(&wr);
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Settings::SaveWindowPos(POINT{ wr.left, wr.top });
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return 0;
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}
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+3
CalculatorWindow.h
+3
CalculatorWindow.h
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BOOL CreateStandalone();
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void ToggleVisible();
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bool IsShown() const { return m_shown; }
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void PlaceInitial();
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POINTL CalcMinimalSize() const;
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POINTL CalcIdealSize() const;
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MESSAGE_HANDLER(WM_THEMECHANGED, OnThemeChanged)
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MESSAGE_HANDLER(WM_CLOSE, OnClose)
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MESSAGE_HANDLER(WM_LBUTTONDOWN, OnLButtonDown)
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MESSAGE_HANDLER(WM_EXITSIZEMOVE, OnExitSizeMove)
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END_MSG_MAP()
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// Handler prototypes:
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LRESULT OnThemeChanged(UINT uMsg, WPARAM wParam, LPARAM lParam, BOOL& bHandled);
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LRESULT OnClose(UINT uMsg, WPARAM wParam, LPARAM lParam, BOOL& bHandled);
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LRESULT OnLButtonDown(UINT uMsg, WPARAM wParam, LPARAM lParam, BOOL& bHandled);
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LRESULT OnExitSizeMove(UINT uMsg, WPARAM wParam, LPARAM lParam, BOOL& bHandled);
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void Paint(HDC hdc, const RECT& rcPaint) const;
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// UINT_PTR SetUpdateTimer();