[Bug]: Wrong `LongText` position

[PWagner1]

From @ckak07

Hello. I am using the LongText property to visualize the connection state of my interfaces to the users. But sometimes the position of the text is incorrect:

In 95% of the time the position is correct. I am not able to tell you the trigger which causes this. This is the correct position:

Can you tell me what my problem is?

I am using this code to set the connection state string:

LongForeColor = connectionStateTextColor;  

LongText = connectionStateText;  TreeView.Refresh(); 

Every time I get this error I also get the following Exception:

Exception thrown: 'System.ArgumentException' in System.Drawing.dll
Ungültiger Parameter.

Extracted embedded document 'System.Drawing\Graphics.cs' to 'C:\Users\wieckowskic\AppData\Local\Temp.vsdbgsrc\0b9159ab0ba1693197c456715007381a34512a2d7e5ec0069dfcb48674a027cd\Graphics.cs'
Extracted embedded document 'Krypton.Toolkit\AccurateText.cs' to 'C:\Users\wieckowskic\AppData\Local\Temp.vsdbgsrc\c5005e343da174ed67ae8cb92cccbefbeb8e9be31c7bf6dcfd50f23c496d886e\AccurateText.cs'

and this is the call stack:

I could debug the error and I found out that the following line returns the value '2':

int num = SafeNativeMethods.Gdip.GdipMeasureString(new HandleRef(this, NativeGraphics), text, text.Length, new HandleRef(font, font.NativeFont), ref layoutRect, new HandleRef(stringFormat, stringFormat?.nativeFormat ?? IntPtr.Zero), ref boundingBox, out codepointsFitted, out linesFilled); 

Looking at the API reference of this native call showed me that the value '2' means 'InvalidParameter = 2'. Looking at the parameters of this call showed me that font.NativeFont is null. So this is the reason why I get this exception. I don't know what is causing the error and how I can fix it.

I am using this option in my manifest file:

<dpiAware xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">true</dpiAware>

Maybe this could help you to figure out what the problem is.

I set a breakpoint to System.Drawing.Font.Dispose and the breakpoint hits after some time (round about 10 Minutes). This is the call stack:

The application runs without any interaction. Why is krypton disposing the font?

I found the bug. There is an bug in the class PaletteMicrosoft365Base. When the event OnUserPreferenceChanged is fired the method DefineFonts will be called. the first line of this method calls DisposeFonts();. During this time the font.nativeFont become null and I get the exception. Using Krypton.Toolkit.KryptonCustomPaletteBase and setting the BasePalette solves this problem.