![]() ![]() This->label3 = gcnew System::Windows::Forms::Label This->favoriteColorComboBox = gcnew System::Windows::Forms::ComboBox This->ageUpDownPicker = gcnew System::Windows::Forms::NumericUpDown This->label2 = gcnew System::Windows::Forms::Label This->label1 = gcnew System::Windows::Forms::Label This->nameTextBox1 = gcnew System::Windows::Forms::TextBox System::Windows::Forms::ErrorProvider^ favoriteColorErrorProvider System::Windows::Forms::ErrorProvider^ nameErrorProvider System::Windows::Forms::ErrorProvider^ ageErrorProvider System::Windows::Forms::ComboBox^ favoriteColorComboBox System::Windows::Forms::NumericUpDown^ ageUpDownPicker System::Windows::Forms::TextBox^ nameTextBox1 Public ref class Form1: public System::Windows::Forms::Form The SetError method is called with or without appropriate error text during a control's Validated event, depending upon the content in the control. The example sets error icon options using the BlinkRate and BlinkStyle properties and the SetIconAlignment and SetIconPadding methods. The example creates a Form that contains a TextBox control, a NumericUpDown control, and a ComboBox control, each validating its content, and an ErrorProvider for each control. The following code example demonstrates using the ErrorProvider class to notify the user of a data entry error. IExtenderProvider ISupportInitialize Examples Implements IExtenderProvider, ISupportInitialize Inheritance Implements IExtenderProvider Public Class ErrorProvider Interface ISupportInitialize Public Class ErrorProvider Public class ErrorProvider :, , type ErrorProvider = class public ref class ErrorProvider : System::ComponentModel::Component, System::ComponentModel::IExtenderProvider public ref class ErrorProvider : System::ComponentModel::Component, System::ComponentModel::IExtenderProvider, System::ComponentModel::ISupportInitialize public class ErrorProvider :, If(WindowState = FormWindowState.Provides a user interface for indicating that a control on a form has an error associated with it. Protected override void WndProc(ref Message m) Public static extern int RegisterWindowMessage(string message) Public static extern bool PostMessage(IntPtr hwnd, int msg, IntPtr wparam, IntPtr lparam) Public static readonly int WM_SHOWME = RegisterWindowMessage("WM_SHOWME") Public const int HWND_BROADCAST = 0xffff this class just wraps some Win32 stuff that we're going to use send our Win32 message to make the currently running instance Static Mutex mutex = new Mutex(true, "") Īpplication.SetCompatibleTextRenderingDefault(false) In the class of my application main I created a static named Mutex: static class Program Knowing that I could use a mutex for this (but never having done itīefore) I set out to cut down my code and simplify my life. While this works, itīrings on a lot of overhead, and I wanted something cleaner. Instance of my myapp.exe in the process list. Today I wanted to refactor some code that prohibited my applicationįrom running multiple instances of itself. The words belong solely to the blog owner at Sanity Free Coding. ![]() I'm reproducing the content of the article here for posterity. That makes me worry that eventually it might disappear, and with it, the advocated solution. ![]() UPDATEĪs of, the article I linked to above is still active, but the blog hasn't been updated in a while. That's a very nice touch that the other Mutex solutions described here do not address. Second, the article shows how to bring the existing instance of the application to the foreground when the user tries to start another instance. But as it is, I do not use the Microsoft.VisualBasic assembly, and I'd rather not add an unnecessary dependency to my project. If my project already had a dependency on that assembly, I would probably advocate using the approach shown in another answer. The approach described by the article is advantageous for two reasons.įirst, it does not require a dependency on the Microsoft.VisualBasic assembly. Here is a very good article regarding the Mutex solution.
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