Develop Reference

RichTextBox doesn't start selection on mouse down when the form has not focus

I'm using WinForms and on my Form I have a RichTextBox. When my form is out of focus but visible and I try to highlight/select text, it does not allow me to until the form or textbox itself has focus.
I've tried:
txtInput.MouseDown += (s, e) => { txtInput.Focus(); }
but to no avail and I can't seem to find anything online about this issue.
When testing with another program like Notepad, it does possess the desired behavior.

MouseDown is too late.
This is a workaround for sure, but may be all you need:
private void txtInput_MouseMove(object sender, MouseEventArgs e)
{
txtInput.Focus();
}
or of course:
txtInput.MouseMove += (s, e) => { txtInput.Focus(); }
As it is it may steal focus from other controls on your form when you move over the textbox. If this is a problem you could prevent it by checking if your program is active using one the of answers here..

You can make the selection manually using MouseDown and MouseMove events. The answer is based on Taw's first idea:
int start = 0;
private void richTextBox1_MouseDown(object sender, MouseEventArgs e)
{
start = richTextBox1.GetTrueIndexPositionFromPoint(e.Location);
richTextBox1.SelectionStart = start;
}
private void richTextBox1_MouseMove(object sender, MouseEventArgs e)
{
if (e.Button.HasFlag(MouseButtons.Left))
{
var current = richTextBox1.GetTrueIndexPositionFromPoint(e.Location);
richTextBox1.SelectionStart = Math.Min(current, start);
richTextBox1.SelectionLength = Math.Abs(current - start);
}
}
And here is the codes for GetTrueIndexPositionFromPoint method which has taken from Justin:
public static class RichTextBoxExtensions
{
private const int EM_CHARFROMPOS = 0x00D7;
public static int GetTrueIndexPositionFromPoint(this RichTextBox rtb, Point pt)
{
POINT wpt = new POINT(pt.X, pt.Y);
int index = (int)SendMessage(new HandleRef(rtb, rtb.Handle), EM_CHARFROMPOS, 0, wpt);
return index;
}
[DllImport("User32.dll", EntryPoint = "SendMessage", CharSet = CharSet.Auto)]
private static extern IntPtr SendMessage(HandleRef hWnd, int msg, int wParam, POINT lParam);
}

This worked for me;
Extend RichTextBox and override WindowProc with this
protected override void WndProc(ref Message m) {
const int WM_MOUSEACTIVATE = 0x21;
if (m.Msg == WM_MOUSEACTIVATE) {
// Take focus to enable click-through behavior for setting selection
this.Focus();
}
// Let the base handle the event.
base.WndProc(ref m);
}

This soulution didn't work for me since my child window had a TextBox that would lose focus when I would hover over the RichTextBox. After some trial and error, I've managed to find another solution:
private const int WM_PARENTNOTIFY = 0x0210;
private Form Form = new Form(); // Your Form here!
private RichTextBox RTB = new RichTextBox(); // Your RichTextBox here!
protected override void WndProc(ref Message m)
{
if ((m.Msg == WM_PARENTNOTIFY) && (Form != null) && (Form.Visible) && (GetChildAtPoint(PointToClient(Cursor.Position)) == RTB))
{
RTB.Focus();
}
base.WndProc(ref m);
}
The WM_PARENTNOTIFY message can be sent multiple times (including when the main Form is being initialized) so it is important to check that that your Form isn't null otherwise you'll receive an exception.

ListView ContextMenuStrip for column headers

I display a different ContextMenuStrip when I right click the ListView column header, and another inside ListView.
class ListViewExx : ListView
{
public ContextMenuStrip HeaderContextMenu { get; set; }
int contextMenuSet = 0;
protected override void WndProc(ref System.Windows.Forms.Message m)
{
base.WndProc(ref m);
switch(m.Msg)
{
case 0x210: //WM_PARENTNOTIFY
contextMenuSet = 1;
break;
case 0x21: //WM_MOUSEACTIVATE
contextMenuSet++;
break;
case 0x7b: //WM_CONTEXTMENU
if(contextMenuSet == 2 && HeaderContextMenu != null)
HeaderContextMenu.Show(Control.MousePosition);
break;
}
}
}
This works very well. The problem is the FIRST TIME I right click inside the ListView - the headers contextMenuStrip is shown.

Relying on the activation state is too hacky. It is far simpler, the WM_CONTEXTMENU message passes the handle of the window that generated the message. So you can simply compare it to the handle of the listview. If it doesn't match then you know it was the header control:
protected override void WndProc(ref System.Windows.Forms.Message m)
{
base.WndProc(ref m);
if (m.Msg == 0x7b) { //WM_CONTEXTMENU
if (m.WParam != this.Handle) HeaderContextMenu.Show(Control.MousePosition);
}
}
Technically you should use LVM_GETHEADER but this should work just fine.

I've tried finding a clean way to get Column Header Rectangle of a ListView to check if the Point at which user right-clicks is in a Column Header or not. However, I've just found that the Column Header Rectangle of a ListView seems to be revealed only in a DrawColumnHeader event handler. This solution is all what I can think of to help you out:
public class CustomListView : ListView
{
//This contains the Column Index and its corresponding Rectangle in screen coordinates.
Dictionary<int, Rectangle> columns = new Dictionary<int, Rectangle>();
public CustomListView()
{
OwnerDraw = true;//This will help the OnDrawColumnHeader be called.
}
protected override void OnDrawItem(DrawListViewItemEventArgs e)
{
e.DrawDefault = true;
base.OnDrawItem(e);
}
protected override void OnDrawSubItem(DrawListViewSubItemEventArgs e)
{
e.DrawDefault = true;
base.OnDrawSubItem(e);
}
protected override void OnDrawColumnHeader(DrawListViewColumnHeaderEventArgs e)
{
columns[e.ColumnIndex] = RectangleToScreen(e.Bounds);
e.DrawDefault = true;
base.OnDrawColumnHeader(e);
}
protected override void WndProc(ref Message m)
{
if (m.Msg == 0x7b)//WM_CONTEXTMENU
{
int lp = m.LParam.ToInt32();
int x = ((lp << 16) >> 16);
int y = lp >> 16;
foreach (KeyValuePair<int, Rectangle> p in columns)
{
if (p.Value.Contains(new Point(x, y)))
{
//MessageBox.Show(Columns[p.Key].Text); <-- Try this to test if you want.
//Show your HeaderContextMenu corresponding to a Column here.
break;
}
}
}
base.WndProc(ref m);
}
}

Moving 2 forms at the same time

I'm stuck a little bit here. I'm trying to move 2 forms at the same time without using OnMove, LocationChanged, Docking etc.
The only way to interact with their locations is to override WndProc. Something which might be helpful is that form A is owner of form B. So whenever A is moved I want to move B as well. Not to the same location but the same distance.
protected override void WndProc(ref Message m)
{
if (m.Msg == 0x0084)
{
Form[] temp = this.OwnedForms;
if(temp.Length > 0)
{
/* moving temp[0] to the same ratio as this form */
}
m.Result = (IntPtr)2;
return;
}
base.WndProc(ref m);
}
Both A and B have the same WndProc since they are 2 objects from the same class.

It doesn't make any sense to avoid using the LocationChanged event:
private Point lastPos;
protected override void OnLoad(EventArgs e) {
base.OnLoad(e);
lastPos = this.Location;
}
protected override void OnLocationChanged(EventArgs e) {
base.OnLocationChanged(e);
foreach (var frm in this.OwnedForms) {
frm.Location = new Point(frm.Location.X + this.Left - lastPos.X,
frm.Location.Y + this.Top - lastPos.Y);
}
lastPos = this.Location;
}
protected override void WndProc(ref Message m) {
// Move borderless window with click-and-drag on client window
if (m.Msg == 0x84) m.Result = (IntPtr)2;
else base.WndProc(ref m);
}

I managed to solve the problem:
protected override void WndProc(ref Message m)
{
Form temp = this.Owner;
if (m.Msg == 0x0084)
{
m.Result = (IntPtr)2;
return;
}
if (m.Msg == 0x0216 && temp != null)
{
if (!movedonce)
{
oldlocationx = this.Location.X;
oldlocationy = this.Location.Y;
movedonce = true;
}
temp.Location = new Point(temp.Location.X + this.Location.X - oldlocationx, temp.Location.Y + this.Location.Y - oldlocationy);
oldlocationx = this.Location.X;
oldlocationy = this.Location.Y;
}
base.WndProc(ref m);
}

Is it possible to make a C# form non movable [duplicate]

How would i go about stopping a form from being moved. I have the form border style set as FixedSingle and would like to keep it this way because it looks good in vista :)

Take a look at this link. You might be interested in option #3. It will require you to wrap some native code, but should work. There's also a comment at the bottom of the link that shows an easier way to do it. Taken from the comment (can't take credit for it, but I'll save you some searching):
protected override void WndProc(ref Message message)
{
const int WM_SYSCOMMAND = 0x0112;
const int SC_MOVE = 0xF010;
switch(message.Msg)
{
case WM_SYSCOMMAND:
int command = message.WParam.ToInt32() & 0xfff0;
if (command == SC_MOVE)
return;
break;
}
base.WndProc(ref message);
}

You can set the FormBorderStyle property of the Form to None
this.FormBorderStyle=System.Windows.Forms.FormBorderStyle.None

I found this to stop the form from moving (its in c#)
protected override void WndProc(ref Message m)
{
const int WM_SYSCOMMAND = 0x0112;
const int SC_MOVE = 0xF010;
switch (m.Msg)
{
case WM_SYSCOMMAND:
int command = m.WParam.ToInt32() & 0xfff0;
if (command == SC_MOVE)
return;
break;
}
base.WndProc(ref m);
}
Found here

Try to override WndProc:
protected override void WndProc(ref Message m)
{
const int WM_NCLBUTTONDOWN = 161;
const int WM_SYSCOMMAND = 274;
const int HTCAPTION = 2;
const int SC_MOVE = 61456;
if ((m.Msg == WM_SYSCOMMAND) && (m.WParam.ToInt32() == SC_MOVE))
{
return;
}
if ((m.Msg == WM_NCLBUTTONDOWN) && (m.WParam.ToInt32() == HTCAPTION))
{
return;
}
base.WndProc(ref m);
}

It's not all pretty (there is some flashing going on when you try to move the form), but you can use the LocationChanged property to keep the form where you want it:
private Point _desiredLocation;
// assign the _desiredLocation variable with the form location at some
// point in the code where you know that the form is in the "correct" position
private void Form_LocationChanged(object sender, EventArgs e)
{
if (this.Location != _desiredLocation)
{
this.Location = _desiredLocation;
}
}
Out of curiousity; why would you want to do this?

In Windows, the WS_CAPTION style is the non-client area that allows your window to be moved with a mouse. So the easiest way to do what you want is to remove this style from your window.
However, if you need to have a caption and still achieve what you want, then the next style would be to capture the WM_NCHITTEST message and check for HTCAPTION. If the code is HTCAPTION, return NTNOWHERE instead. This will prevent the default window procedure from executing the default move window thing.

It's not a good practice to make your form immovable. I'd think agfain about it if I were you.
Anyway, you can do this by overridding the WinProc to disable the [Move] menuitem from the system menu.
[DllImport("user32.dll")]
private static extern Int32 EnableMenuItem ( System.IntPtr hMenu , Int32uIDEnableItem, Int32 uEnable);
private const Int32 HTCAPTION = 0×00000002;
private const Int32 MF_BYCOMMAND =0×00000000;
private const Int32 MF_ENABLED =0×00000000;
private const Int32 MF_GRAYED =0×00000001;
private const Int32 MF_DISABLED =0×00000002;
private const Int32 SC_MOVE = 0xF010;
private const Int32 WM_NCLBUTTONDOWN = 0xA1;
private const Int32 WM_SYSCOMMAND = 0×112;
private const Int32 WM_INITMENUPOPUP = 0×117;
protected override void WndProc(ref System.Windows.Forms.Message m )
{
if (m.Msg == WM_INITMENUPOPUP)
{
//handles popup of system menu
if ((m.LParam.ToInt32() / 65536) != 0) // 'divide by 65536 to get hiword
{
Int32 AbleFlags = MF_ENABLED;
if (!Moveable)
{
AbleFlags = MF_DISABLED | MF_GRAYED; // disable the move
}
EnableMenuItem(m.WParam, SC_MOVE, MF_BYCOMMAND | AbleFlags);
}
}
if (!Moveable)
{
if (m.Msg == WM_NCLBUTTONDOWN) //cancels the drag this is IMP
{
if (m.WParam.ToInt32() == HTCAPTION) return;
}
if (m.Msg == WM_SYSCOMMAND) // Cancels any clicks on move menu
{
if ((m.WParam.ToInt32() & 0xFFF0) == SC_MOVE) return;
}
}
base.WndProc(ref m);
}
Also, you can handle OnMove event of your form. But I think this will cause some flickering:
private void Form1_Move(object sender, EventArgs e)
{
this.Location = defaultLocation;
}

Just change the FormBorderStyle property to None.

change the Form property StartPostion to Manual.
Then, handle the LocationChanged event:
private void frmMain_LocationChanged(object sender, EventArgs e)
{
Location = new Point(0, 0);
}

Go to form events-> Location changed
write the following code
Location = new Point(this.Width,this.Height);

I would question your need to make the form unmovable. This doesn't sound nice. You could of course save the location of the window when the window closes and reopen the window into that position. That gives the user some control over where the window should be located.

You can subscribe to the Form.Move event and reposition from it.

Just reset the location on formlocation_changed event to where it was i.e. set the Form.Location to a variable before it's moved and when the user tries to move it, it will go back to the variable location you set it to.

Private Sub MyFormLock()
Me.Location = New Point(0, 0)
End Sub
Private Sub SearchSDR_LocationChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.LocationChanged
Call MyFormLock()
End Sub

You can try:
this.Locked = true;

unselectable node in TreeView

I have TreeView control on winform. I desire to make several nodes unselectable. How can I achive this.
There is only one idea in my mind - custom drawn nodes, but may be more easier way exists? Please advice me
I have already try such code in BeforeSelect event handler:
private void treeViewServers_BeforeSelect(object sender, TreeViewCancelEventArgs e)
{
if (e.Node.Parent != null)
{
e.Cancel = true;
}
}
But effect it gained is not appropriate. Node temporary get selection when I am holding left mouse button on it.
Thanks in advance!

You could completely disable mouse events in case you click on a not-selectable node.
To do this, you have to override TreeView a shown in the following code
public class MyTreeView : TreeView
{
int WM_LBUTTONDOWN = 0x0201; //513
int WM_LBUTTONUP = 0x0202; //514
int WM_LBUTTONDBLCLK = 0x0203; //515
protected override void WndProc(ref Message m)
{
if (m.Msg == WM_LBUTTONDOWN ||
m.Msg == WM_LBUTTONUP ||
m.Msg == WM_LBUTTONDBLCLK)
{
//Get cursor position(in client coordinates)
Int16 x = (Int16)m.LParam;
Int16 y = (Int16)((int)m.LParam >> 16);
// get infos about the location that will be clicked
var info = this.HitTest(x, y);
// if the location is a node
if (info.Node != null)
{
// if is not a root disable any click event
if(info.Node.Parent != null)
return;//Dont dispatch message
}
}
//Dispatch as usual
base.WndProc(ref m);
}
}