Validate new Thread to ensure there is text

all the validation will takes place for the editor body over here in  Forums - Create/Edit Post UI.js file , you can add some regex to validate if there was any text rather than images 

	context.attachBodyChangeScript(saveButton.evolutionValidation('addCustomValidation', 'body', function()
			{
				var body = context.getBodyContent();
				var beginningMatches = body.match(/\[quote((?:\s*)user=(?:\"|"|").*?(?:\"|"|"))?\]/g);
				var endingMatches = body.match(/\[\/quote(?:\s*)\]/g);
				if ((beginningMatches == null) != (endingMatches == null))
					return false;

				return body.length > 0 && ((beginningMatches == null && endingMatches == null) || beginningMatches.length == endingMatches.length);
			},
			context.bodyRequiredText, '#' + context.wrapperId + ' .field-item.post-body .field-item-validation'
		));

all the validation will takes place for the editor body over here in  Forums - Create/Edit Post UI.js file , you can add some regex to validate if there was any text rather than images 

	context.attachBodyChangeScript(saveButton.evolutionValidation('addCustomValidation', 'body', function()
			{
				var body = context.getBodyContent();
				var beginningMatches = body.match(/\[quote((?:\s*)user=(?:\"|"|").*?(?:\"|"|"))?\]/g);
				var endingMatches = body.match(/\[\/quote(?:\s*)\]/g);
				if ((beginningMatches == null) != (endingMatches == null))
					return false;

				return body.length > 0 && ((beginningMatches == null && endingMatches == null) || beginningMatches.length == endingMatches.length);
			},
			context.bodyRequiredText, '#' + context.wrapperId + ' .field-item.post-body .field-item-validation'
		));